I have an issue with Xbox Remote Play on my Series S. Every time I try to connect to my console outside my home network, I get a connection error where my console is found, but my mobile device can't connect to it. I tried everything. I used several guides and opened all necessary ports in my router. While my Xbox gives me a go to use Remote Play, I still get the error. I even tried using a wired connection instead and also turned off private relay, but it still doesn't work. Connecting inside my home network works absolutely fine. Also, a weird thing is that the remote control feature over mobile data works.
Does anyone know a solution for that or am I screwed?
I'm guessing that it's because you are using a 5G Modem as your Internet. You are behind a CG-NAT which can cause all kinds of funky things with streaming outside of your own WiFi.
Without seeing anything myself, it sounds like you've done everything correctly on your Xbox and home network's end. Have you tried using a different device for remote play?