I have had this issue ever since upgrading my Vigor 2820VN to v3.3.0 even though the settings haven't changed.

Basically I have two VOIP phones that connect to an external SIP provider (sipgate.co.uk) on non-standard ports -5160 and 5260. From what I can see, the ports are all still forwarded correctly however only one phone (the first one to connect) will remain connected.

Does anyone have any suggestions on where to look for the issue?

Thanks

Tim