Apple ID / Icloud verification Issue

Hi, Both children's Ipad failed to connect to icloud over the weekend. This seems to have locked them out of Netflix etc. I tried a bunch of stuff, then I called tech support after 1 hour on the phone, we wiped both ipads, clean install. And still no luck, the ipad will still not log in. I've since wiped both ipads again, and trying to setup them up under my account. It takes my password, sends a code to my phone, then i get a verification failed message.

I purchased 200 Gigs of icloud storage last week, that is the only change I'm aware of.

I had this happen about 3 months ago to a 3rd ipad (older one) and I was told hardware was broken in the old ipad, so we bought a new ipad. This now happens a 2nd and 3rd time, on two different ipads on two different child accounts. I do not think this is a hardware issue on my end anymore. I'm not willing to spend 700 to buy two new ipads. The ipads in question now are an air, and a 5th generation. Both are on 12.3 for OS.

I feel like there is an issue with the serial numbers or something on the server end at apple.

I've been through every message board on the internet. I've tried every trick I could fine. Date / time etc.

Help! My kids want Netflix...