Please follow this step-by-step guide for installing LTE Router Teltonika RUT240
Remove cover plate (5 screws, some older chargers was made without cover plate)
2. Insert router on the upper rail. Connect router on power supply (red wire → V+, black wire →V-)
3. Connect router and ARM board with UTP cable. Connect antennas and secure wires.
4. Cover canals and screw cover plate back