I think maybe the device type is different, the carrier will generally have some restrictions for the router type of device.
What do you mean? It is a modem, like Collie is. I think some setting is messing connection, while ZTE doesnt. I just can figure it out which settings Collie has that are messing it up.
The router has NAT forwarding and can share hot spots with multiple devices. To limit the use of multiple devices, carriers may do some restrictions. ZTE modems do not have the problem of using multiple devices.
Only one device is connected to Collie? Can i change NAT rules or something to match ZTEs?