On the old 6.x firmware it was straight forward to configure WAN failover. You select the main WAN, configure the Failover Configuration (IP to monitor) and selected a WAN Failover.
However, on the 7.x firmware it doesn’t seem that straight forward?
I can help clarify setting up a WAN failover with the new 7.x firmware UI.
Here at our Wiki (RUTX11 Failover - Teltonika Networks Wiki) you can find an example on how to setup specific WAN failover for interface priority & IP to check functionality against.
Below can be done while using 07.07.1 Firmware.
If you are logged into the WebUI and have the configuration option toggled to Advanced, you should also be able to start a simple failover from the Network → WAN section, if any of the interfaces are disconnected.
Here with the default out of the box configuration, the interfaces will try to reach out to their default route for any type of reply.
You can toggle which interfaces you would like to have failover, say for example primary WAN interface then 2ndary Mobile interface. And you can drag the interfaces up or down in priority, with the interface at the top with the highest priority.
I would recommend setting your primary WAN to flush on connection. This would ensure that you have routing done through your primary WAN connection again & not still through your secondary connection, once the primary is back online.
I would not add any Flush to your 2ndary WAN connection, unless you are also configuring a 3rd WAN failover. In which case I would do the same for the 2ndary WAN to flush on connection.
My only caution on this would be for Mobile WAN connections. If you are in an area with very poor cell reception where your SIM is dropping/connecting again constantly it could cause problems with Flushing connections too often.
I would recommend checking your connection strength & modifying the SIM slot’s Low Signal Reconnect if necessary.