How to resolve Apple Watch Cellular connection issues?

Okay I bought the Apple Watch SE in January 2022, and set up a data plan. This past October, I purchased the Ultra 2, paired it to my phone and was able to use the data plan on both watches. Could make calls, send and receive texts, check my email etc…

This past Saturday, I just upgraded phones from the 13 Pro Max to the 15 Pro Max. They made me unpair my watches at the store, and I immediately paired the Ultra 2 back while still at the Apple Store, when I came home I paired the SE as well as the family members 7. They all worked (I only have the two data lines) I sat here and test called my phone from all 3 watches.

I went to my third shift Job around 1 am Sunday and my Ultra 2 was constantly losing connection, it consistently had the little red X popping up and disappearing, but I couldn’t make any calls or send any texts, I thought perhaps my son turned my phone off at home. Nope! I forgot to toggle on the automatic switch in the watch app. Flipped it on when I got home and all was good… Both the SE and the Ultra 2 once again had connections, would display the weather, both showed my cellular provider. All was as it had been!

Here I am Tuesday night, trying to figure out what happened, the Ultra 2 had cellular data when I went to work, suddenly the weather was just blank around 5 pm. I reset it all night hoping that the connection would pop up but, nope! Looked at the network settings and it said “no sim.”

Well, I come home from work and unpair it then repair it, apparently my sim has been transferred to the Ultra, now the SE is doing the same thing!

I read a few questions here asking if it’s possible to use two watches on the same data line and I saw some answers saying absolutely not! But, I had been for the past 7 months, now I can’t! So what gives? I’m with T-mobile if that matters…

[Re-Titled by Moderator]