ok looks like depending on your provider/network. even if you have the same isp like your son, it could be the isp/network.
first i would try out to change the dns directly on the ipad, do you know how to change dns on ipad ? i never did it on ipad/apple products, please google a bit if you dont know how
try this dns servers and look if it changes /gets better
Cloudfare : 1.0.0.1 or 1.1.1.1
Google: 8.8.8.8 or 8.8.4.4
Open DNS: 208.67.222.222 or 208.67.220.220
DNS Watch: 82.200.69.80 or 84.200.70.40
did you try other apps, try it once with gse smart iptv - the thing in your case is to find a solution (maybe not the most that you wish)
i can tell you, that from 100 customers 1-3 have sometimes problems between 1-2 weeks but in most cases the problem gets solved from alone (i cant tell you technically why, maybe changes on ip adresses on servers, any changes from your network which we dont know or recognize)
and for now at least, have you got other devices ? one example, one customer did have problems with his smart tv then he tried his fire tv stick and there was no problem