When doing a test with this page: test.webrtc.org
There is one test result that is different from a working/non-problem location:


Reflexive connectivity does not pass.
Here it is said this is called hairpinning and is not a reason per se why it would not work:
https://support.google.com/googlenest/t ... 9875?hl=en
As far as i can gather the issue must be modem/firewall related, perhaps ports are blocked or symmetric NAT (https://networkengineering.stackexchang ... symmetric#)
Other useful pages i found:
https://blog.addpipe.com/troubleshootin ... on-issues/
https://github.com/webrtc/testrtc/issues/176
https://webrtc.github.io/samples/src/co ... ickle-ice/
Did anyone run into this issue before and have some recommendations how to work around this?