I sometimes have a need to go from WIFI to a Cellular Data or to Network Bluetooth connection during the Collab session. In the previous version this was a simple re-connection, which was handled automatically. In the Ultra version this is broken. When the original connection stops the screen comes up with the Reconnect button. Once you press reconnect it says that you are already logged into the session. You have to refresh the browser, then sign in again, in order to get connected to the session.
It may be that going from one IP to another causes this problem, but it makes sense to recognize the browser that is connecting via a cookie (or similar where not legal), so the connection can be seamless.