As an FYI, to get the tablo app to recognize that port forwarding was working I had to disable remote access then enable it. This is in the settings page under Tablo Connect.
I kept thinking it was the modem/router/gateway and spent a few hours with Xfinity tech support. I gave up. Then I decided to try to disable it and re-enable it.
I also had to setup UPnP for port forwarding in the gateway’s web page.
I also had to setup the device’s port forwarding in the Xfinity’s app using the private port numbers and the TCP protocol as shown on the Tablo app. The Xfinity app did NOT have manual configuration for port forwarding nor did the web page.
Yes, I had to mess with 2 gateway configuration programs: its web page and the app. Thank you Xfinity.
I had hours and hours of frustration due to the Tablo App NOT automatically refreshing when testing. Nor any sort of app help link icon on this indicating that the enable/disable should be done.
This was for:
a legacy Tablo,
A Xfinity XB8-T gateway, and
wired Tablo to gateway
Additionally, the gateway is using “Advanced Security” set to medium.