Since updating to macOS 27 beta 3 (build 26A5378j), my Mac is unable to establish any new TCP connections. This affects all outbound traffic regardless of destination or protocol, while ICMP (ping) continues to work normally. Steps to reproduce: Update to macOS 27 beta 3 (26A5378j) Connect to a standard home Wi-Fi network (no VPN, no proxy, no enterprise MDM profile) Attempt any outbound TCP connection (curl, git pull, ssh) Expected behavior: Connections to any HTTPS endpoint or SSH server should establish normally. Actual behavior:
curl -4 -v https://github.com
curl -4 -v https://google.com
both hang indefinitely at "Trying [IP]..." — the TCP handshake never completes
git pull
over both HTTPS and SSH remotes times out with "Failed to connect... Timeout was reached" ping github.com and ping google.com both succeed normally and immediately This confirms the issue is isolated to TCP connection establishment, not DNS resolution or general network connectivity Issue persists identically across multiple reboots
System info:
macOS 27.0 beta 3, build 26A5378j Connected via personal home Wi-Fi (Bbox router) No VPN, no proxy, no enterprise security software
Additional context:
Multiple other users have reported identical symptoms on this same build across MacRumors forums and Reddit, describing broken connections in Firefox, Opera, Dropbox, Telegram, and Music/iTunes purchases, while Safari continues to work. Reported workarounds from other affected users include:
Disabling "Limit IP Address Tracking" on the network interface Disabling all Network Extensions under System Settings → General → Login Items & Extensions Uninstalling CrowdStrike Falcon or similar EDR/security software (where present)
This was working correctly on both beta 1 and beta 2, the regression appears to have been introduced specifically in beta 3.
Thank you for looking into this. I found the cause.
Running systemextensionsctl list revealed an active Network Extension:
com.sentinelone.network-monitoring (SentinelOne EDR agent, version 25.3.4/8365) — [activated enabled]
This is corporate endpoint security software (SentinelOne), installed as part of my company's device management policy. I disabled this Network Extension and the issue is immediately and fully resolved. curl, git pull, and ssh all connect normally now, with no other changes made.
