We were both on WIFI and got kicked from the game at the same time. then when she logged in, still on the same WIFI , this started.
We did try if on mobile data thinking that us being on the same WIFI grinding, but it did not help.
She was unable to get in last night when we checked before bed, but this morning we were able to get her logged in.
If it happens over WIFI again I'll update here.
You mentioned it being a possible mobile data issue. Is there somewhere I can go to keep updated on that?