I also do not run pulseaudio, if that is a requirement (and it looked like it back then when I looked at it) the linux-client is useless to me.
Pulseaudio is not a requirement, ring can choose ALSA if you prefer.
> but my router has no settings for nat-pmp
Maybe I exagerated a bit. Ring comes by default configured to use TURN and you can also setup STUN. The problem with this is that they are not distributed.
If you want true P2P, you have to use upnp or nat-pmp, Ring can use any of the two. I don't know if it is because I get impatient, but it takes forever to connect. Just upnp should suffice but I get paranoid and think, maybe it's upnp that is not working. Then I enable nat-pmp in the router and open the nat-pmp port in the laptop. Sometimes I get so impatient that I also open (temporarily) every port in the laptop just in case.
That's great to know :)
I'll keep an eye on Ring. Something like this in a working state would be great, But it should not take forever to connect and should be stable (more or less). According to this thread the project still has a lot to do, and it might be that the p2p approach is just not a good one for the problem at hand. Riot/Matrix looked more promising in that regard.