Totally agree on all points!
My only issue was with the assertion that OP could comfortably do away with the certs/https. They said they were already using certs in the post and I wanted to dispel the idea that they arguably might not need them anymore in favour of just using headscale as though one is a replacement for the other.
That’s pretty cool!
Although that’s probably what op is actually asking for, I don’t think it’s a modem. It’s a router with an access point.
It does have SFP for a fibre connection and pcie and USB for you to potentially add a modem or whatever else you want.
I’m guessing OP is just looking for a wifi router? Otherwise we’d need to know what kind of modem they’re looking for, like Cellular? VDSL? HFC? Satellite? It depends on the internet connection. Different parts of the world need very different kit.