onConnect and onDisconnect in IOS

[phonganh010193]

I use props onDisconnect and onConect to log to server. But there is a problem with the device.
For ipad software version 13.5.1 after disconnecting from the network and turning it back on, props onDisconnect and onConnect worked and logged on to the server.
For ipad software version 15.5 and above, props onDisconnect and onConnect are not working. no log after re-enabling network connection?
Cause why? can you help me explain? Please