GTP No longer working/NO SERVICE Internationally

Hello. I am currently abroad in Belize and having difficulty with roaming on iPhone 13 despite having global pass activated and currently do not have 4 bar signal, it says NO SERVICE. The phone does connect to local carriers but does not display 4g/5g/LTE. I’ve contacted 4 agents and they said the network around me has been down (which is false everyone is connected to it), they said it would connect once I added back GTP, which was removed because it wasn’t working, false again still not connect to a network.  I have tried. 

- restarting

- hard restarting

- network reset

- toggle airplane mode

- toggle roaming

- ensuring no VPN

- software update

- updating carrier settings

- manually selecting network from the options listed.

I appreciate the help