I recently installed 10 yealink T46G phones on our up to date Version 11 Multi tenant server. The phones are using STUN. The customer is on the second tenant (so 6060). They have been working great for a week up until this morning. When the users got in all the blf buttons on the phone showed red x's as if they were not registered to the system. Incoming call setup - All calls would ring a ring group and in that ring group all phones were in that group. However only one phone would ring (extension 106), but when looking at the Extension Status in the admin console it would show Ext 103 as ringing and being picked up and answered (but it was not Ext 103 it was Ext 106). After about 10 seconds the call would drop. I had the customer simply reboot the phone and now it seems everything is back to normal. But I do feel this will happen again. What may cause this behavior? The phone side firewall, the phones themselves?