> I also do not run pulseaudio

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.