I have an old mac pro in my office. The operating system is big sur. It uses wifi to connect to the internal network and Bluetooth to connect to the external network of the mobile phone. Unfortunately, I recently upgraded Monterey and the Bluetooth network connection disappeared.Bluetooth PAN is missing
macOS big sur，bluetooth connection to mobile phone network
macOS Monterey，“connection to network” disappeared.
More unfortunately, in order to test whether the problem was caused by upgrading to macOS Monterey, I also upgraded another mac air to Monterey, so all my computers could not connect to the Bluetooth network.