Originally Posted by azuziel
I've never been able to get this to work either. Also related, unlocking will remove LTE, permanently.
Unlocking shouldn't remove LTE. All you have to do is make sure to correct the APN, as it might change, and flash back to your newer modem afterwards.
Are you sure your ODIN drivers are set up right? Try reinstalling/manually updating the drivers. They never like to work very well. You could also try Mobile ODIN since you have an unlocked bootloader.