Apple+ TV won't stay signed in on X1 cable box or satellite box

I’m having a problem with my elderly mom’s X1 box.  I have a family Apple One subscription which allows me to share AppleTV with 5 family members (each uses their ICloud login).  I’m 400 miles away so I am trying to help support her via FaceTime remotely.

My mom uses the AppleTV+ app on her X1 and signs in with the QR code using her iPhone and authenticates.  The problem is that after the first login it logged her out on the X1 and when she went back it said she needed to log in again.  So she scanned the QR code and her iPhone says she’s logged in and that her TV will reset but nothing happens on the X1.   I had her reboot the X1 with her voice remote and repeat the process with no success, I even had her clear out the cache on the x1 (ugh thanks for that 3 hr saga via FaceTime of having to go through walking her through logging in all of the streaming services manually via the remote all over again), but again no help, it still logs out after the first login and the second time it says you’re already logged in on the iPhone after the QR code authentication but the X1 never updates.

If the answer is a new X1 box that’s going to require a service call because she’s not savvy enough to do it herself and I’m 400 miles away.  My concern though with that is that while mailed or picked up in store x1’s are new or refurbished sealed in package, the one she got 9 months ago when her gateway and box were replaced by a service person was a old used box that has never worked properly and constantly lags.  For example it takes 10 minutes to reboot and 3-5 minutes to load apps.  But when she called the local office (not tech support because she won’t do offshore support) she was told that was normal and another service call to exchange she would have to pay for because she had the most up to date box.

anyways, that’s what I’m dealing with trying to help her…. Do you have any ideas or suggestions on what I can do to get AppleTV to work for her short of doing my setup for her next time I visit? (ditching and returning the X1, getting her an AppleTV device , downloading Xfinity Stream, have her watch cable channels and dvr via the stream app, and access the rest of the apps directly that way?  — Not sure I really want to do that because that will be a huge change but this is becoming untenable)