More information is needed.
Normal mesh wifi setup would be: Telus Actiontec gateway > Google Wifi on port 1 of Actiontec gateway. Optik TV and range extender (if used for wireless TV box) on the remaining ports on the Actiontec. If you're on fibre, there's one other possible setup but a gigabit switch would be required.
There's your problem. Google Wifi is not currently compatible or capable of handling multicast data (what IPTV uses). The Actiontec is configured specifically for multicast TV traffic. Users have been asking Google to add that feature for some time now but Google hasn't done it yet.
My working configuration in my smart panel is T3200M > my own router on port 1 (then to all my personal devices from it hardwired and wireless). Port 2+ are all hardwired for my Optik boxes.
The Google Wifi is not alone as multicast data is not supported on a fair number of routers out there. Were you just using Google Mesh as an option to extend wifi? Ever consider putting an ethernet switch behind one of the TV boxes and plugging in the Google Wifi there if you just need better wifi coverage? I have ethernet switches behind both of my TV boxes. Telus also has a mesh wifi solution where you get two modules for a lower cost than just one Google Wifi device.