Whilst posting my "Reply" I kept getting the message that Safari was unable to carry out my directions as the "server was not available". Ended up posting twice!!
Did you manage to sort your problem as I have exactly the same problem and I'm pulling my hair out trying to find a solution?!
Tbh no we didn't really get an answer to it other than the fact the apple devices drive our connection mental 🙈 b.t tried everything they could to no avail.
We got my daughter an unlimited data sim card for her phone and she says upstairs on her apple devices using her phone as a hot spot and this seens to have solved our issue as a fix.
Reason i know its not fixed completely is because she recently smashed her phone and since then she tries to use her ipad and it causes havoc again.
Its very frustrating for sure!!
Sounds more like an apple issue. I'm still not sure apple backup has not been disabled or rate limited otherwise why are there not hunderds of complaints here.
Tried everything with the devices too.
It doesnt effect every apple device neither though cos my mother in laws and my sons works fine.