Constantly buffering on computer browser

The last 2 days, I have not been able to stream Dtv on my computer. Wired connection; ATT Fiber (running 938 down; 1095 up; 5 ping). Have tried Firefox, Chrome, and Edge. Same things happens on all 3.  (No app, just browser)

I log into the page; go to any channel. Buffers slightly, then starts; and about 5 seconds later, it starts buffering and the video freezes. About a quarter of the time, the sound freezes also, but the rest of the time, it continues to run. If I reload, everything resets, and it happens again.  I cannot get any saved shows to load either; it just sits blankly.

No issues with any other streaming service; Hulu/Disney+, Paramount+, Peacock, Starz, HBO...all work fine on all 3 browsers. It's only Dtv I am having trouble with. 

Nothing updated or changed on my system. Did get a new video card put in 9 days ago, but had no issues until yesterday.

Deleted all browsing history, cache, etc. Rebooted computer, Dtv box, Internet. 

Any ideas on how to fix this, before I hop onto support and put them to work?