Optimum and Fios are two isps in the US.
> Try running a UDP-only DNS server from home on some random port.
No reason to run DNS.
However, I run openvpn udp between three houses (fios, Comcast, cablevision) for nearly 15 years. It’s pretty common, works fine.
Again in the US... cable, fiber and dsl internet service comes with a public mostly unfiltered IPv4 address, the address is dynamic but in practice it is extremely stable.
End of story.
No idea why you’re acting like such an imbecilic tool in this thread. The whole time I have mentioned that this is the case for major US “landline” ISPs. Yes there are plenty of counterexamples, not sure what point you’re trying to prove.