Hey mate, just reading your post. Exactly the same thing has happened to me. Working absolutely fine. Suddenly cannot stream / download and watch UHD content. However, if I switch to HD, can watch after 1-2% has downloaded.
Have restarted my box. Have internet speed of 300mb/s.
I had an engineer out to it. He fitted a sky hub direct to router. Then set the devices to only connect to the hub. Everything back to normal operation. The guy said it's a compatibility issue with the router/software
