@Rixxxy I think I found the problem.
When you go into the Opera Settings, like I had, there's a whole WebRTC area. (https://i.imgur.com/FQLU9xN.gif)
For me, at least, this setting was set to Disable non-proxied UDP. (https://i.imgur.com/ex4mr7U.png)
Switching this to the recommended setting or anything else should solve your problem after closing Opera GX and re-opening it, at least for me. If this didn't help you, then I'm very sorry.
(I actually had the same problem and tried fixing it myself, since nobody else has been a help.)