I use Sidecar with a 2019 16" MBP (Monterey 12.1) and an 12.9" iPad Pro (iPadOS 15.2). The connection is over USB with an Apple USB-C Lightning cable. When I unplug the iPad, all networking connectivity on the Mac is lost. This happens 100% of the time.
The iPad will display "Lost Connection. The session will resume automatically when the connection improves." There's a button to "Disconnect". The disconnect button doesn't do anything and reconnecting the cable doesn't resume the connection.
At this point, the iPad will no longer reconnect with Sidecar. Mac apps with network connectivity begin to hang. The spinning beachball starts to take over. I've tried shutting down the network adapter in Terminal using
sudo ifconfig en0 down but then Terminal hangs. The Mac requires a hard reset.
I've looked in the logs but I haven't been able to identify anything that could be related. I also don't know what the Sidecar system is called to refine my search for log entries.
Any suggestions on how to troubleshoot this issue? Has anyone else encountered a similar problem?