Cannot connect to plex insecure connection

I had troubles with switching between managed users and with accessing plex through the windows phone app. After reboot it seems everybody can access my server (friends outside the network, so the server is running) except me. I get “The selected server cannot be reached securely. An insecure connection may be possible.”.

So I think what happened is that something went wrong and now I need to login the server again, but I cannot connect to the server securely. I can remember I once setup to not allow insecure connections… So how to solve this? Can I change this setting in a settingsfile and if so, wich one?
I’m running Plex Server on a qnap nas.

Thanks!

Rob

And here is my problem: https://forums.plex.tv/discussion/214870/secure-connections-broken-since-latest-plex-web-update#latest

Setting was found in preferences.xml by the way.