I am currently using Comcast equipment because I use the Roku app as a receiver for Comcast service. I’d like to build out my home network but ran into a problem last time I made things all beautiful and elaborate with pi-hole, sophos home antivirus appliance, and other non-comcast hardware. My Roku kept saying that it was not on the home network and I didn’t have time to troubleshoot, so I decided to save the project for when I actually had some time.

The first question I want to answer is how does the Xfinity stream app determine it is on the local network? Does it somehow connect to the Xfinity gateway, does it check the external IP, is there some checking using DNS, or some combination of all of the above?

If nobody has to answer here, what would be the best way to determine this? Wireshark? What exactly would I be looking for?

I need to figure this out so that I don’t block anything, or can explicitly permit access to whatever the Xfinity stream app needs to function.

Thank you everybody for ideas here Before I can start building my dream home network I need to solve this problem.