I have the same problem with WiFi printing using MacOS, though the USB printing direct laptop to printer works fine.
The main difference from the OP is that I don’t know and can’t find the printer IP address. It’s not showing up on the Pepwave Status page and I have no idea how to locate it.
A search of terms such as “OSX print” and “MacOS print” brings up only two or three threads. Links to some relevant topics would be quite helpful. Thanks.
This one came up searching “Brother”: Printer problems I’ll try it but it isn’t exactly the same problem. More threads would be nice.