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TZ400 in high availbilty mode with 4G USB adapter


I have 2x TZ400 firewalls running in high availbility mode. The firewalls are behind a cisco C881 service router from our internet provider.

I woud like to install a 4G USB adapter for internet backup purposes. The 4G adapter is DWM222 from d-link and supported by sonicwall. But the 4G adapter makes no connection. I have tried different connection settings but no luck.

I had the 4G adapter connected to the sonicwall for serveral hours but suddenly the sonicwall could not ping to the cisco router anymore. No internet was availabe since then. I removed the 4G adapter and restarted the sonicwall and cisco router and everything was up again.

Is it possible to use a 4G adapter in combination with a high availbilty setup? Has anyone experience with this?

Why is the 4G adapter not working? I know the adapter is OK because I have test it on another devices.

Category: Entry Level Firewalls


  • TKWITSTKWITS All-Knowing Sage ✭✭✭✭

    I'd say you'd need two cellular adapters for a true HA setup.

    I'm speculating, but what likely happened when you lost connectivity was HA decided to failover to the device without the cellular connection. Since that device had settings assuming the cellular was there but didn't, it caused the routing to get borked.

  • shiprasahu93shiprasahu93 Moderator

    Hello @Reinder,

    Welcome to the SonicWall community.

    Unfortunately, the 4G USB adapters are not compatible with HA. Since it can be either plugged into the primary or secondary device. The network set up needs to be identical when set up in HA.


    Shipra Sahu

    Technical Support Advisor, Premier Services

  • TKWITSTKWITS All-Knowing Sage ✭✭✭✭

    @shiprasahu93 For clarification, even if you had two 4G USB adapters (one for each primary and secondary unit) HA wouldn't function properly??

    I would think this would be an accepted configuration.

  • ReinderReinder Newbie ✭


    I have only 1 4G adapter. But I cannot get this adapter to work.

    What would be the best solution for an internet backup?

  • AjishlalAjishlal All-Knowing Sage ✭✭✭✭

    Hi @Reinder

    Instead using the 4G USB modem, I would recommend to use the 4G LTE normal modem and insert your SIM.

    Then configure your 4G modem LAN interface for the Sonicwall primary & HA unit. So in this scenario you would get fail-over connection as well as it will support HA.

  • ReinderReinder Newbie ✭
  • ReinderReinder Newbie ✭


    Can you maybe expain how to set this up with a TZ400 sonicwall?

    The sonicwall is connected to internet with WAN interface. I would like to keep it this way.

  • AjishlalAjishlal All-Knowing Sage ✭✭✭✭

    Hi @Reinder

    You have to configure one more additional WAN interface in your sonicwall and connect to the 4G modem LAN1 port & LAN2 connect to the HA unit.

  • TKWITSTKWITS All-Knowing Sage ✭✭✭✭
    edited June 30

    This wouldn't be true HA since you are relying on a single 4G modem and SIM card... If someone at Sonicwall could confirm or deny using two 4G USB adapters would be accepted we could know for sure! @shiprasahu93 @Micah @Saravanan

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