I Have a Nexus 5 running on Android 6 (latest updates installed)
I have entered all the right info from de provider, portforwarding in de router is OK.
Tried Transportype is TLS and TCP. Both no difference. Got als code 503 Transport Failure, no transports left to try,
Tried stun settings, default no effect, Customer
Few months ago it worked fine, but recently I can't connect anymore.
Can you give some suggestions