Playing video (DVR) through the Stream app used to work; has not worked for 3-4 days

I had the Xfinity Stream app set up on my Apple TV device, iPad, and Amazon Fire TV stick. For the last year or so, I could watch video through this app on all devices, both in my home and in a nearby hotel (extended power outage).

As of 3-4 days ago, the Stream app stopped playing video or showing pictures on both iPad and Fire stick. (I haven't tried the Apple TV app—it kept forgetting my login and I got tired of entering the info over and over.) The apps can connect to the Comcast server; I can see the channel listings for live TV, and it correctly shows the text listings of my current DVR recordings and scheduled recordings. But on both the main page (recently watched and recorded/suggested channels/shows) and on the DVR recordings page, it shows blank colored squares instead of the expected thumbnail images for the shows.

If I try to watch a DVR recording, the Fire TV Stream app shows a busy indicator for ~5 minutes, tries to fall back to the On Demand version (which I never ever want) and then reports an error. "Well that didn't go as planned", etc. etc., no error code. Live TV through the Stream app sometimes errors out, sometimes connects for around a minute but then plays live TV successfully. At one point I got an error message "Playback Issue :: 1001. We're sorry but we're unable to play this video right now. Error: 4" (I don't remember if I got that from DVR playback or live TV).

Attempting to play back DVR on the iPad Stream app shows the correct video duration and channel name with a busy indicator, then if I keep the screen awake it times out and offers to show me the On Demand version (which, again, I never want, and wish the app would not suggest). Tapping the button to see the On Demand version also times out.

Through our cable boxes, live TV and DVR playback work absolutely fine.

I logged out of the iPad Stream app and logged back in—no change in behavior.

(I tried to troubleshoot this through the Web site chatbot. It recognized Stream app as an option, then when it started that troubleshooting flow, it asked which TV boxes had problems. Note that the Stream app has nothing to do with TV boxes, and resetting TV boxes would never fix the Stream app. Bad bot.)