Datto Networking Appliance (DNA): LTE Failover



This article describes the LTE failover feature on the Datto Networking Appliance (DNA).


  • Datto Networking Appliance (DNA)


The Datto Networking Appliance can automatically fail over to a 4G LTE cellular network in the event of a WAN interruption. The appliance will automatically switch into failover mode if it detects no connectivity over its WAN port. The carrier to which it fails over varies by region. See our Datto Networking Appliance (DNA): Region And Hardware Specifications article for more information about service provider regions and availability.

All devices dependent on an Internet connection will continue to function as usual. You may also notice a marginal decrease in connection speed due to cellular bandwidth limitations.

When the DNA detects restored connectivity on its WAN port, it will exit failover mode and resume regular operation. You will not need to reset the connection manually.

Functionality changes during LTE failover

During LTE failover, the following functionality changes occur:

  • The LTE modem will receive an IP address, but any provided DDNS names will not work while the device is in failover.
  • Port forwarding is non-functional.
  • IPsec functionality changes in the following ways:
    • If the DNA is the initiator and it goes into failover, the tunnel will still work.
    • On DNA-to-DNA IPsec connections, if the responder enters failover mode, but the initiator still has a WAN connection to the ISP, the DNA will change the responder to the initiator tunnel will work.
    • If both units in a DNA-to-DNA connection are in failover, IPSec will not work.
  • ClientVPN users will be unable to connect due to carrier-grade NAT preventing uninitiated inbound connections. This case applies to both IKEv2 and OpenVPN.

Testing Failover Mode

The DNA's Test Failover option allows you to simulate a network interruption to evaluate the device's performance in 4G LTE mode.

Testing cellular failover will temporarily shut down the DNA's WAN connections, interrupt existing network connections, and activate the device's cellular failover functionality. Your network will function in a degraded state while the failover test runs. Use caution when testing this feature in a production environment.

To access the LTE/4G Failover UI, log into the DNA web interface, and click Status.

mceclip0.pngFigure 1: Status (click to enlarge)

The WAN Details card is on the right-hand side of the page. Click the Test Failover button in the LTE/4G Failover category to begin the test.

Figure 2: WAN Details card (click to enlarge)

While the test runs, the DNA will display the banner shown in Figure 3. The test can take up to a minute to complete. 

Figure 3: Failover mode warning banner (click to enlarge)

The DNA will return to the WAN connection on its own after the test finishes.

If no cellular service is available

If the modem cannot find cellular service, the UI will display the status message shown below.

mceclip1.pngFigure 4: No signal status (click to enlarge)

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