How do I connect my device to the GSM/LTE network?

First, you need to connect LTE antennas for the device (notice if you have moving object where the device will be located, you need to connect two antennas, for stable connection)

After that go to device configuration menu, go to the System/Network/GSM/GSM/LTE configuration tab and check in the Default SIM Slot menu whether the SIM card is right in the slot, if everything is correct, you have successfully connected to GSM/LTE network