I have noticed that HandOff between mac and iPhone doesn't work when connected to VPN.
Steps to reproduce when using ExpressVPN:
- install ExpressVPN native client on mac, connect to local wifi, then to VPN server, take note of server
- install ExpressVPN native client on iPhone, connect to same wifi, then to same VPN server
- try HandOff of webpage from Safari in iPhone to Safari in mac -> doesn't work, Safari on mac displays message "opening webpage from HandOff" but page doesn't load (stays blank, no 404 or other error shown)
- disconnect from VPN in both mac and iPhone and retry same experiment -> Safari opens the page without problems
Actually, how does HandOff work under the hood? It seems to require both Bluetooth and Wifi. I guess Bluetooth is being used for the transfer itself while Wifi is used to check connection to iCloud. https://support.apple.com/en-us/HT204681