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Explore the networking protocols and technologies used by the device to connect to Wi-Fi networks, Bluetooth devices, and cellular data services.

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NSProcessInfo hostName holds the process for 30+ seconds
We have used ::gethostname to retrieve hostname in our tunnel provider extension and found it returns "localhost" on iOS 17+. So we changed to use [[NSProcessInfo processInfo] hostName]. However it often caused 30+ delay in the extension process on a few devices and always returns "localhost". The sysdiagnose shows a lot of DNS query logs as below: default mDNSResponder 2025-03-19 17:15:12.453769 +0800 75281: 0x11ad501 [R80937] DNSServiceCreateConnection START PID[79767](ACExtension) default mDNSResponder 2025-03-19 17:15:12.453892 +0800 75281: 0x11ad501 [R80938] DNSServiceQueryRecord START -- qname: <mask.hash: 'fNnSAdyuhKXqCny8+neXvw=='>, qtype: PTR, flags: 0x15000, interface index: -1, client pid: 79767 (ACExtension), name hash: 84de01e1 default mDNSResponder 2025-03-19 17:15:12.458395 +0800 75281: 0x11ad501 [R80939] DNSServiceQueryRecord START -- qname: <mask.hash: '2X6qN/YT0yh2psKwrGWokg=='>, qtype: PTR, flags: 0x15000, interface index: 0, client pid: 79767 (ACExtension), name hash: f25c923e default mDNSResponder 2025-03-19 17:15:12.462924 +0800 75281: 0x11ad501 [R80940] DNSServiceQueryRecord START -- qname: <mask.hash: 'peyRWEblLKbNvcOXPjSeMQ=='>, qtype: PTR, flags: 0x15000, interface index: 0, client pid: 79767 (ACExtension), name hash: 83323cc4
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131
Mar ’25
Reconnecting NEPacketTunnelProvider
Hi, In my attempt to reconnect NEPacketTunnelProvider, when there is a network change, I am making use of self.reasserting and setTunnelNetworkSettings, and I am calling it with similar parameters as during the startTunnelWithOptions callback and making sure to make a new call for setting the includedRoutes: NEPacketTunnelNetworkSettings.IPv4Settings.includedRoutes = @[NEIPv4Route.defaultRoute]; This works sometimes, when I switch to a new network, but most of the time the traffic flow stops and it only works when I switch back to the first network. The only difference I could see in the routing table when it works is when there is a presence of Apple Specific network routes as follows: 17.57.145.133 link#22 UHWIig utun4 17.57.145.135 link#22 UHWIig utun4 17.57.145.137 link#22 UHWIig utun4 or 13.107.246.47 link#22 UHW3Ig utun4 17.57.145.148 link#22 UHWIig utun4 17.57.145.149 link#22 UHWIig utun4 37.252.171.52 link#22 UHWIig utun4 37.252.173.215 link#22 UHWIig utun4 Note: utun4 has index of 22 or some other combination of routes for Apple, I am not sure what these routes are for but they are present when NEPacketTunnelProvider starts. When switching to a new network and calling setTunnelNetworkSettings of NEPacketTunnelProvider, in any case when these routes are not present the traffic flow stops and it works otherwise. Switching back the first network, brings back these routes and the traffic flow continues, although it also goes through the same setTunnelNetworkSettings call and logic. I am not sure if these route table entries could be the culprit, because I did try to add them manually and that didn't help but my guess is that some system calls are failing for some unknown reason which might be the reason for the missing routes and some other configuration needed for proper traffic flow, which I am not seeing. Any help or information would be greatly appreciated. Thanks.
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103
Mar ’25
wifi connect fail
Dear Apple: We encountered a problem when using the Wi-Fi connection feature. When calling the Wi-Fi connection interface NEHotspotConfigurationManager applyConfiguration, it fails probabilistically. After analyzing the air interface packets, it appears that the Apple device did not send the auth message. How should we locate this issue? Are there any points to pay attention to when calling the Wi-Fi connection interface? Thanks
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424
Mar ’25
Fixed Private Wi-Fi Address Changes after Update
I had noticed that my slaac address changed between one beta and the other, but wasn't sure. Now with the RC 15.4 RC (24E247) I made point of preserving the info before updating from the previous beta. What I noticed is that not only the slaac address changes, but also the my ether address, even though I have it on Fixed in the settings. Is it expected that the ether, and the slaac, not be rotated after a OS update?
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79
Mar ’25
Completion handler blocks are not supported in background sessions
When I try to implement the new Background Task options in the same way as they show in the WWDC video (on watchOS) likes this: let config = URLSessionConfiguration.background(withIdentifier: "SESSION_ID") config.sessionSendsLaunchEvents = true let session = URLSession(configuration: config) let response = await withTaskCancellationHandler {       try? await session.data(for: request) } onCancel: {       let task = session.downloadTask(with: request))       task.resume() } I'm receiving the following error: Terminating app due to uncaught exception 'NSGenericException', reason: 'Completion handler blocks are not supported in background sessions. Use a delegate instead.' Did I forget something?
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2.7k
Apr ’25
Network Content Filter based on packets
Hi, I built a system that can detect and block Short Form Videos like Instagram Reels and Youtube Shorts. It works by connecting the iphone to a VPN and then do statistics on network packets (no decryption). I was wondering the feasibility of porting this to run on device. Functionality wise I would need: packet interception, packet drop, DNS query interception. I saw that Content filter providers could be something to look into, but then I read an article of how you would have to have a managed device which is not ideal for the end user. New to apple development, the lack of snippets and code examples is confusing.
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69
Apr ’25
Socket Becomes Unresponsive in Local Connectivity Extension After Lock Screen
I’m developing an app designed for hospital environments, where public internet access may not be available. The app includes two components: the main app and a Local Connectivity Extension. Both rely on persistent TCP socket connections to communicate with a local server. We’re observing a recurring issue where the extension’s socket becomes unresponsive every 1–3 hours, but only when the device is on the lock screen, even if the main app remains in the foreground. When the screen is not locked, the connection is stable and no disconnections occur. ❗ Issue Details: • What’s going on: The extension sends a keep-alive ping packet every second, and the server replies with a pong and a system time packet. • The bug: The server stops receiving keep alive packets from the extension.  • On the server, we detect about 30 second gap on the server, a gap that shows no packets were received by the extension. This was confirmed via server logs and Wireshark).  • On the extension, from our logs there was no gap in sending packets. From it’s perspective, all packets were sent with no error.  • Because no packet are being received by the server, no packets will be sent to the extension. Eventually the server closes the connection due to keep-alive timeout.  • FYI we log when the NEAppPushProvider subclass sleeps and it did NOT go to sleep while we were debugging. 🧾 Example Logs: Extension log: 2025-03-24 18:34:48.808 sendKeepAliveRequest() 2025-03-24 18:34:49.717 sendKeepAliveRequest() 2025-03-24 18:34:50.692 sendKeepAliveRequest() ... // continuous sending of the ping packet to the server, no problems here 2025-03-24 18:35:55.063 sendKeepAliveRequest() 2025-03-24 18:35:55.063 keepAliveTimer IS TIME OUT... in CoreService. // this is triggered because we did not receive any packets from the server Server log: 2025-03-24 18:34:16.298 No keep-alive received for 16 seconds... connection ID=95b3... // this shows that there has been no packets being received by the extension ... 2025-03-24 18:34:30.298 Connection timed out on keep-alive. connection ID=95b3... // eventually closes due to no packets being received 2025-03-24 18:34:30.298 Remote Subsystem Disconnected {name=iPhone|Replica-Ext|...} ✅ Observations: • The extension process continues running and logging keep-alive attempts. • However, network traffic stops reaching the server, and no inbound packets are received by the extension. • It looks like the socket becomes silently suspended or frozen, without being properly closed or throwing an error. ❓Questions: • Do you know why this might happen within a Local Connectivity Extension, especially under foreground conditions and locked ? • Is there any known system behavior that might cause the socket to be suspended or blocked in this way after running for a few hours? Any insights or recommendations would be greatly appreciated. Thank you!
5
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156
Apr ’25
Crash heppen when i set to false to the usesClassicLoadingMode in URLSessionConfiguration
when i set the flag false to the usesClassicLoadingMode, then the application is getting crashed Ex: let config = URLSessionConfiguration.default if #available(iOS 18.4, *) { config.usesClassicLoadingMode = false } Crash log : *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFBoolean objectForKeyedSubscript:]: unrecognized selector sent to instance 0x1f655c390' *** First throw call stack: (0x188ae52ec 0x185f69a7c 0x188b4f67c 0x1889fcb84 0x1889fc4f0 0x191393bc8 0x1889ec8a0 0x1889ec6e4 0x191393ad0 0x191344dac 0x191344b58 0x107cfa064 0x107ce36d0 0x191343fcc 0x1891b3b18 0x1892dae58 0x189235c60 0x18921e270 0x18921d77c 0x18921a8ac 0x107ce0584 0x107cfa064 0x107ce891c 0x107ce95d8 0x107ceabcc 0x107cf5894 0x107cf4eb0 0x212f51660 0x212f4e9f8) terminating due to uncaught exception of type NSException
1
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154
Apr ’25
XPC doesn't work with network extension on app upgrade
Our app has a network extension (as I've mentioned lots 😄). We do an upgrade by downloading the new package, stopping & removing all of our components except for the network extension, and then installing the new package, which then loads a LaunchAgent causing the containing app to run. (The only difference between a new install and upgrade is the old extension is left running, but not having anything to tell it what to do, just logs and continues.) On some (but not all) upgrades... nothing ends up able to communicate via XPC with the Network Extension. My simplest cli program to talk to it gets Could not create proxy: Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service named blah was invalidated: failed at lookup with error 3 - No such process." UserInfo={NSDebugDescription=The connection to service named bla was invalidated: failed at lookup with error 3 - No such process.} Could not communicate with blah Restarting the extension by doing a kill -9 doesn't fix it; neither does restarting the control daemon. The only solution we've come across so far is rebooting. I filed FB11086599 about this, but has anyone thoughts about this?
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4.2k
Apr ’25
macOS Sequoia No Route to Host on first request. Retries work.
My app has local network permission on macOS Sequoia and works in most cases. I've noticed that after unlocking my MacBook Pro, the very first request will regularly fail with a No Route to Host. A simple retry resolves the issue, but I would have expected the very first request to succeed. Is this is a known issue on macOS Sequoia or by design? I'd prefer not to add a retry for this particular request as the app is a network utility.
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2.1k
Apr ’25
XPC listener initialized in System Extesnion invalidates incoming connection under certain conditions
I found a problem where a process tries to connect to System Extension and connection is invalidated. XPC listener has to be disposed and initialized again. This happens when System Extension executes tasks in following order: NSXPCListener initialized NSXPCListener.resume() NSProvider.startSystemExtensionMode() Result: Connection is invalidated and not only that the client has to retry connection, nut also System Extension must reinitialize listener (execute step 1 and 2). However if I call NSProvider.startSystemExtensionMode() NSXPCListener initialized NSXPCListener.resume() It works as expected and even if the connection is invalidated/interrupted, client process can always reconnect and no other action is necessary in System Extension (no need to reinitialize XPC listener), In Apple docs about NSProvider.startSystemExtensionMode() it says that this method starts handling request, but in another online article written by Scott Knight I found that startSystemExtensionMode() also starts listener server. Is that right? PLease could you add this info into the docs if it is so? https://knight.sc/reverse%20engineering/2019/08/24/system-extension-internals.html I would like to use following logic: Call NSProvider.startSystemExtensionMode() only under certain circumstances - I have received some configuration that I need to process and do some setup. If I don't receive it, there is no reason to call startSystemExtensionMode() yet, I don't need to handle handleNewFlow() yet. Connect XPC client to System Extension under certain conditions. Ideally communicate with client even though System Extension is not handling network requests yet, that is without receiving handleNewFlow(). Basically I consider XPC and System Extension handling network requests as separate things. Is that correct, are they separate and independent? Does XPC communication really depend on calling startSystemExtensionMode()? Another potential issue: Is it possible that XPC listener fails to validate connection when client tries to connect before System Extension manages to complete init and park the main thread in CFRunLoop? Note: These querstions arose mostly from handling upgrades of System Extension (extension is already running, network filter is created and is connected and new version of the app upgrades System Exension). Thanks.
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1.4k
Apr ’25
Network Service Order for IoT Ethernet device
I am making a USB attached IoT device that follows the Matter approach to connectivity (IP/mDNS/DHCP). I am having conflicts with it as it appears to MacOS as an Ethernet adapter and this is causing it to be assigned as a "default" route, interfering with routing when my Mac is connected to NAT based WiFi. I'd like to be able to hint to MacOS & iPadOS that this is not a routable private network, the subnet should be respected and a default route should not be assigned to it, otherwise the order of the device connection is used by the IP routing tables and I am concerned my non-routable private network will initialize before Wifi and block NAT based internet connectivity. How can I hint to MacOS/iPadOS "this is not a routable private network, this is not a NAT, do not assign me a default route beyond the subnet I have provided you."
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117
Apr ’25
Access BSSID MacOS
I don't understand what permissions need to be given for this code to operate. I cannot seem to work out why I'm not able to see a BSSID. I think I've given sandbox the appropriate permissions AND I've added some to the Target Properties for good measure. Yet, cannot get BSSID. import SwiftUI import CoreWLAN import CoreLocation struct ContentView: View { @State private var currentBSSID: String = "Loading..." var body: some View { VStack { Image(systemName: "globe") .imageScale(.large) .foregroundStyle(.tint) Text("Current BSSID:") Text(currentBSSID) } .padding() .onAppear(perform: fetchBSSID) } func fetchBSSID() { if let iface2 = CWWiFiClient.shared().interface() { print("✅ Found Wi-Fi interface: \(iface2.interfaceName ?? "nil")") } else { print("❌ No Wi-Fi interface found") } if let iface = CWWiFiClient.shared().interface(), let bssid = iface.bssid() { currentBSSID = bssid } else { currentBSSID = "Not connected" print("✅ BSSID: \(currentBSSID)") } } } #Preview { ContentView() } Output - WifI interface is found but BSSID is not found.
2
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205
Apr ’25
Issues with Opening iOS Settings from App
Hi there! We are working on our SkyElectric App which is being developed in Flutter framework, where we need user to connect with the Wifi of the the inverter. We are trying to direct user to WiFi Settings page of the iOS in general settings where all the available WiFi Networks are listed but unfortunately user is being directed to App's Settings page. We are using package of app_settings and launcher. I've read that Apple changed a policy in 2019 where it restricts Apps to navigate to OS pages. Question: Could you please verify if I APPLE allows us to access the General Settings or WiFi Settings through clicking a button in our App name "Open WiFi Settings", If not then Why?
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83
Apr ’25
how to register listener to `NWConnectionGroup` for QUIC
I am trying to make http3 client with Network.framework on Apple platforms. Codes that implement NWConnectionGroup.start with NWListener don't always work with warning below. I assume NWConnectionGroup.newConnectionHandler or NWListener.newConnectionHandler will be called to start connection from the server if it works. nw_protocol_instance_add_new_flow [C1.1.1:2] No listener registered, cannot accept new flow quic_stream_add_new_flow [C1.1.1:2] [-fde1594b83caa9b7] failed to create new stream for received stream id 3 so I tried: create the NWListener -> not work check whether NWConnectionGroup has a member to register or not NWListener -> not work (it doesn't have). use NWConnection instead of NWConnectionGroup -> not work Is my understanding correct? How should I do to set or associate listener with NWConnection/Group for newConnectionHandler is called and to delete wanings? What is the best practice in the case? Sample codes are below. Thanks in advance. // http3 needs unidirectional stream by the server and client. // listener private let _listener: NWListener let option: NWProtocolQUIC.Options = .init(alpn:["h3"]) let param: NWParameters = .init(quic: option) _listener = try! .init(using: param) _listener.stateUpdateHandler = { state in print("listener state: \(state)") } _listener.newConnectionHandler = { newConnection in print("new connection added") } _listener.serviceRegistrationUpdateHandler = { registrationState in print("connection registrationstate") } // create connection private let _group: NWConnectionGroup let options: NWProtocolQUIC.Options = .init(alpn: ["h3"]) options.direction = .unidirectional options.isDatagram = false options.maxDatagramFrameSize = 65535 sec_protocol_options_set_verify_block(options.securityProtocolOptions, {(_: sec_protocol_metadata_t, _: sec_trust_t, completion: @escaping sec_protocol_verify_complete_t) in print("cert completion.") completion(true) }, .global()) let params: NWParameters = .init(quic: options) let group: NWMultiplexGroup = .init( to: .hostPort(host: NWEndpoint.Host("google.com"), port: NWEndpoint.Port(String(443))!)) _group = .init(with: group, using: params) _group.setReceiveHandler {message,content,isComplete in print("receive: \(message)") } _group.newConnectionHandler = {newConnection in print("newConnectionHandler: \(newConnection.state)") } _group.stateUpdateHandler = { state in print("state: \(state)") } _group.start(queue: .global()) _listener.start(queue: .global()) if let conn = _group.extract() { let data: Data = .init() let _ = _group.reinsert(connection: conn) conn.send(content: data, completion: .idempotent) }
4
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211
Apr ’25
On-demand rules
I've implemented a custom system extension VPN for macOS using Packet Tunnel Provider. The VPN is configured with on-demand, and a rule to always connect whenever there's traffic: onDemandRules = [NEOnDemandRuleConnect()] As expected, if the VPN isn't active, all traffic gets blocked until it is ready. Not expected: In the following scenario, there is some 'traffic leak': Use only WiFi (not wired cable) Connect the VPN Disable the WiFi and wait for the VPN to disconnect Enable the WiFi Some packets are routed outside the VPN, and aren't being blocked Some moments after, all traffic will be blocked, and the VPN will start the 'connecting' process. Is the above scenario a 'known' issue? Can it be a race condition in the OS, where some packets can be sent after the network is brought back before the VPN process starts? Is there any way to fix this problem? P.S: I'm not using flags such as 'capture all network'
3
1
186
Apr ’25
Network Push Provider Wifi Selection Behavior
In our App, we have a network extension with a NEAppPushProvider subclass running. We run the following steps Setup a dual-band wireless router per the following: Broadcasting 2.4 GHz and 5 GHz channels Same SSID names for both channels Connected to the production network to the router DHCP assigning addresses in the 10.1.x.x network Connect the mobile device to the 5 GHz network (if needed, turn off the 2.4 GHz network temporarily; once the device connects to the 5 GHz network, the 2.4 GHz network can be turned back on). Create a NEAppPushManager in the App, using the SSID from the above mentioned network and set it to the matchSSIDs property. Call saveToPreferences() on the push manager to save. A. We have UI that shows the extension has been started and it has connected to the server successfully. Walk out of the range of the 5 GHz channel of the router, but stay within range of the 2.4ghz channel. Wait for the mobile device to connect to the 2.4 GHz channel. Expected: The extension would reconnect to the 2.4ghz network. Observed: The extension does not reconnect. Checking the logs for the extension we see that the following was called in the push provider subclass. stop(with:completionHandler:) > PID: 808 | 🗒️🛑 Stopped with reason 3: "noNetworkAvailable" The expectation is that start() on the NEAppPushProvider subclass would be called. Is this an incorrect expectation? How does the NEAppPushProvider handle same network SSID roaming among various band frequencies? I looked at the documentation and did not find any settings targeting 2.4 or 5 ghz networks. Please advise on what to do.
5
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143
Apr ’25
NetworkFramework and UDP Broadcast Mode (2025)
So it seems the NetworkFramework is still not able to support Broastcast Mode am I correct? As soon as I switch broadcast mode to On in my game I receive console messages instead of receiving data. nw_path_evaluator_create_flow_inner failed NECP_CLIENT_ACTION_ADD_FLOW (null) evaluator parameters: udp, definite, server, attribution: developer, reuse local address, context: Default Network Context (private), proc: 2702288D-96FB-37DD-8610-A68CC526EA0F, local address: 0.0.0.0:20778 nw_path_evaluator_create_flow_inner NECP_CLIENT_ACTION_ADD_FLOW 1FB68D7E-7C9B-47B2-B6AC-E5710CD9C9CD [17: File exists] nw_endpoint_flow_setup_channel [C2 192.168.178.221:52716 initial channel-flow (satisfied (Path is satisfied), interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] failed to request add nexus flow nw_endpoint_flow_failed_with_error [C2 192.168.178.221:52716 initial channel-flow (satisfied (Path is satisfied), interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] already failing, returning nw_endpoint_handler_create_from_protocol_listener [C2 192.168.178.221:52716 failed channel-flow (satisfied (Path is satisfied), interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] nw_endpoint_flow_pre_attach_protocols nw_connection_create_from_protocol_on_nw_queue [C2] Failed to create connection from listener nw_ip_channel_inbox_handle_new_flow nw_connection_create_from_protocol_on_nw_queue failed I won't be able to receive data which is a real shame, so I guess I am stuck with the lower level code: // Enable broadcast var enableBroadcast: Int32 = 1 if setsockopt(socketDescriptor, SOL_SOCKET, SO_BROADCAST, &enableBroadcast, socklen_t(MemoryLayout<Int32>.size)) == -1 { let errorMessage = String(cString: strerror(errno)) throw UDPSocketError.cannotEnableBroadcast(errorMessage) }
1
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148
Apr ’25
How can user allow a content filter after previously choosing "Don't Allow"?
Our enterprise product uses a content filter, normally customers deploy MDM profiles to authorise and allow the content filter to work. Some customers however do not use these profiles, requiring them to enable the system extension in System Settings and allow the content filter via the popup below. If the user selects "Don't Allow", intentionally or by mistake, there does not appear to be an mechanism for them to change their mind and allow it instead. If the user fails to enable the system extension on the first prompt, there is an option to enable if via System Settings. There doesn't seem to be a similar option if they "Don't Allow" the content filter. How can the user allow a previously denied content filter?
2
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148
Apr ’25
How to set NEDNSSettings port, or how to bind on port 53 for MacOS Network Extension?
In my Packet Tunnel Provider, I'm setting the NEDNSSettings to localhost as I have a local DNS server listening on port 53 (this is a dns forwarder which conditionally forwards to different upstreams based on rules). On iOS it works just fine, I'm able to listen on localhost:53 in the Network Extension, then set NEDNSSettings servers to "127.0.0.1". However on macOS due to the port being under 1024, I get a Permission denied OS code 13 error. I'm assuming this is due to the Network Extension not running as root. Can this be changed? This could be rectified if you could customize the port in NEDNSSettings, as the listener could be on port 5353, but it doesn't look like it is possible? Just wondering if there is some other way to accomplish what I'm trying to do in the macOS Network Extension?
6
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536
Apr ’25