I have a PMS at my in-laws house in Pittsburgh and one at my house in Los Angeles. I used to be able to watch live TV from anywhere with my Nvidia Shield but have had problems since about the same time as you.
I can see the PA server in the Shield but the LA one doesn’t even show up. The PA server has not been able to stream live tv for a while now though.
On my laptop I can see both servers and can watch TV from either so what I’ve been doing is pulling up what I want to see on my laptop and casting it to the Shield TV.
It would be nice to have the issue resolved though.