I've been able to replicate this same issue using two networks (not necessarily just wifi networks).
At first glance, it looks like access tokens are being linked to IP's now. Not sure if that's intentional. I remember being able to change networks without any issue.
However, I don't have a proxy nor two wired connections with a different IP to confirm that the IP change is the issue and not some other factor.
I just confirmed that this is still an issue in 2.0.320-stage. This time with a proxy (switching between two different IP addresses) rather than switching across networks. This might be something with the authentication servers, either intentional or not.