Hi,
I tried setting up restund but I couldn't get it to work. Not enough documentation/experience and nobody else seems to be using restund so I gave up. Thread I posted about restund found here- Need help configuring restund for reflexive connectivity
The server software most seem to be using with good results is coturn https://github.com/coturn/coturn but it's not found in the openwrt software repository.
This blog posting with pictures is a nice example as to why a STUN/TURN server is needed for good webrtc connectivity https://blog.addpipe.com/troubleshooting-webrtc-connection-issues/ so that it passes the webrtc reflexive connectivity test, https://test.webrtc.org/
I would love it if someone who set up either restund or coturn could chime in, I have never set one of these up before.
Thanks!