We'll never know. There are many things that could go wrong because VoIP over the public internet is inherently fragile. When I asked for logs so I could look into it, I got cursed at once again.

Grishka wrote very low quality code (an extremely buggy and segfaulty mess of C and C++), combined with little testing in not-so-edge case network conditions.

I managed to improve the situation after weeks of refactoring and testing for my library, and thankfully now it was completely replaced by webrtc.