Upgrade iOS to 18.5, then install app in Xcode and grant permissions to send UDP but it won't work. Then restart device, open this installed app and send UDP again and this time it becomes OK. Repeat these steps and it all goes well. The UDP pod I use in app is CocoaAsyncSocket.
The same thing happens on iPhone 14 Plus and 16 Pro, both iOS 18.5. How to explain this phenomenon, thanks for your help in advance.