How to configure Cellular Dual SIM for Internet Failover on a Mobile Router?

Zyxel_Judy Posts: 990  Zyxel Employee
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You are a network engineer responsible for ensuring uninterrupted Internet connectivity for an office. You have a Mobile Router that supports dual SIM card slots for cellular backup (failover). You want to configure the router to automatically switch between SIM cards in case of Internet failure.


  • A Mobile Router that supports Cellular Dual SIM. (Refer to the FAQ to confirm compatibility)
  • Two SIM cards with active cellular data plans.


  • Navigate to Network Settings on the right-hand menu > Broadband > Cellular Dual SIM
  • Set Preferred SIM Slot: select the "Auto" option.
  • Enable Switch when Detach: toggle the switch to the right to enable it.


  • Default behavior: By default, if both SIM cards are inserted, SIM 1 will be used for the primary Internet connection, and SIM 2 will act as the cellular backup.
  • Auto-Selection: If you change from SIM 1, SIM 2 to Auto, the Mobile Router will choose the SIM card slot you previously selected if it has an inserted SIM card.

To verify that the settings have been applied correctly, you can simulate an Internet failure on the primary SIM by removing it from the primary SIM slot and check if the router switches to the backup SIM.

You have successfully configured your Mobile Router for cellular backup using dual SIM cards. This ensures that your office will have uninterrupted Internet connectivity.

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