How do you fix Not Registered On Network?

So as of saturday my unlocked TMobile Note 4 stopped working as a phone, and won't let me make calls.
Information:
-Was on Dr. Ketan L3 version of his rom when it stopped working
-Using the N910T on AT&T
-IMEI is fine and not damaged, both numbers match (using *#06#)
-It shows bars, but when I go to make a call "Not Registered On Network"

What I've Done:
-Flashed Stock Firmware via Odin (Autoboot, and F.Time Rest checked)
-Factory Reset after odin flash
-Checked APN
-Set on LTE/WCDMA/GSM
-Searched for Networks, finds them, but when I choose AT&T it takes forever and then finally kicks me out and then in notifications, I get the "Not Registered to Network"
-Did the remove the battery thing, and removed sim
-Went to AT&T and got a new sim, worked for 1hr (sporadically) and then went back to "Not Registered on Network"
-At the store I was on phone with AT&T tech trying to troubleshoot the problem and that is when it was working shortly
-Called T-Mobile and checked to see if they blocked my IMEI number, nope they didn't, couldn't help me out further than that
-AT&T was showing that it was a Note 4 so not having that coming up as a Blackberry issue that some reported, so that's not it
-*#0011# shows service limited, but it is unlocked and everything is fine, the IMEI is good, and all is well but the limited service
-Put it in Airplane mode and woke it back from there after 5+minutes
-cleaned the connectors on the sim (new sim anyways so shouldn't really need them)

I'm running out of options, the only thing I can think of being the problem is that I might have started out using this phone on COD2, and when I flashed a COG2 firmware it didn't like that and so my phone's account settings didn't fully transfer.
Also I was messing around with the bands settings (*#2263#) what should they be on? Automatic, LTE/GSM only, or what?