Is there anything "special" about Home Internet? Data care? device? T-Mobile?

So, the SIM started life in device Y (a 5688W home internet box).  I pull it out and put it in device Z, a Moto G7 cell phone with LTE and a mobile hot spot.  Does T-Mobile look at something and flag it that the SIM is no longer IN device Y?  And refuse to let the computer connect to the mobile hot spot?  Or is there something set wrong in the phone or it's locked - though Verizon phones are supposed to unlock after 60 days and this one was in use for a few years.  I presume the APN was set to fast.tmobile??? or whatever it's supposed to be, though I didn't think to check…

I may mess around tomorrow again and see if I can see anything obvious.

Anyhow, we’re at 4:30 and it’s been mostly working around 17-20 Mbps with a few .6 today, but we having hit 7 pm yet.

I may try putting the SIM in the Nighthawk again tomorrow and see what message I get, but I checked the IMEI on AT&T and THEY say something about the device being in someone else's account and they can't unlock it.  So it may be locked…  If I recall (dredging up a really OLD memory), it was originally bought when I was on OTRMobile, which used AT&T, and they went belly up because they were doing something like tablet plans or some such, with unlimited data, and AT&T figured it out…  Or something like that.  So it may ONLY work on AT&T (I normally have a prepaid 100GB plan for it that I use when I'm traveling).

Not sure WHY the 4G phone wouldn’t work.