Please use Nano SIM card (12.3x8.8mm) on the EZR33 router.
Please use activated SIM card in the router. If you are going to use a new SIM card, please follow the instruction from the mobile carrier to activate the SIM card.
Disconnect from the PoE adapter and use the included tool hex wrench to lose all of the four pieces hexagon bolts on the front side of the EZR33 router then open the case.
Use the included SIM pin to push the pinhole gently until the SIM card holder pops out.
Put the primary SIM card on the first slot. Make sure notch in the inside direction and pins face down. There is only one correct way to settle the Nano SIM card into the SIM card holder.
Carefully reposition the SIM card holder in the slot and push it back gently.