Remote Play works only on my home network. How can I set it up to work while travelling?

Hello,

I seem to only be able to connect to Remote Play while I'm on the same network as the Xbox. If I use external wifi or mobile data, I get a black screen, then am returned to the Xbox selection page.

So far, I've tried:

• Port Forwarding instructions from posts like this
  • Port 88 (UDP)
  • Port 3074 (UDP and TCP)
  • Port 53 (UDP and TCP)
  • Port 80 (TCP)
  • Port 500 (UDP)
  • Port 3544 (UDP)
  • Port 4500 (UDP)
  • Port 9002 (UDP and TCP)
• Rebooted the console
• Multiple devices / networks / browsers
• Enabled DMZ
• Not using IPv6

I do not know what other options I have anymore. Anyone have ideas or solutions?