Using android 10 (up to date pixel3a). Zoiper (2.10.5) rings, I answer, and get no audio in either direction. This happens on BOTH lte (rogers.ca) and on my wifi (if i try returning the call the same audio problem happens). Some days, with NO setting changes, it will work... I have rport set for nat, push is used with tls on and sip+rtp. The voip provider is voip.ms (tls enabled) and the incoming calls are showing as answered. I have tried the various combos for nat (stun, and the two rport options). How can this be debuged?