Can't play Amazon Prime videos

I set up a new 4k CCwGTv today. Everything seems to work ok, except for the Amazon Prime app. Every time I try to play a video, I get "Something went wrong. please try again later. For more help, go to amazon.com/videohelp." I tried rebooting the device, switched between 2.4 Ghz and 5 Ghz wifi, I cleared cache and data for the app. None of those attempts fixed it. Does anybody have an idea on how to fix this problem?

Update: I just set it up in a hotel, while out of town, and it works ok here. I'll try it again when I get back home. This makes me think that the problem may be with my router. I have software running on my router that blacklists external IP ranges that are considered risky. Sometimes, good IPs get blocked by accident.