I have the sim the device and it’s active with mint. on the admin page it says the sim isn’t registered and when I click “auto” it times out while “connecting” indefinitely. Any help is appreciated. Thanks.
Do you try to use the sim on an authorized for that network first?
Like make a few calls, sent a few txt and use some data 
Also what router or USB modem you using and what version of the firmware you using.
That would be a better start for troubleshooting
What device are you using?
Mint is using T-Mobile network so it should work.
If the SIM is not registerred, can you pls lock all band 5G and 4G? I assume you are using X3000. If not pls let me know.