On demand programs with Xfinity stream app take 3 minutes to load

On-demand programs using the Xfinity stream app on a Roku TV and an iOS device take 3 minutes to load  Only time it works normally is on cellular on iOS devices. Technician has indicated speed and signal are good for my router and modem which are not Xfinity devices but approved. I have followed all of the suggested fixes. Still no solution. Other subscription services load quickly. My issue is only with the Xfinity streaming app. My Xfinity technician even reached out to another employee who was at home in front of his Roku TV, and he is having the same problem. Needless to say very frustrating for the money I am spending every month.