Each model in the Peplink Balance series supports a single 4G, 3G, WiMAX, or LTE USB modem. To connect a supported cellular modem:
Peplink Balance 20/30/210/310: Plug your supported USB modem into the provided USB port.
Peplink Balance 305/380/580/710/1350: Though these models feature two USB ports, only one USB modem can be connected. Plug your supported USB modem into either one of the Balance’s USB ports.
For Balance routers with dual USB ports, please connect your USB key to either port, as only one can function at a time.
See a list of supported modems here.