We set up one of the LAN ports as a WAN port (see https://wiki.teltonika-networks.com/view/LAN_as_WAN_RutOS
WAN1 is an ethernet connection to the Switch and the Target PC is connected to the Switch.
WAN2 is connected to a RadioA. RadioA communicates with RadioB over the air and RadioB is connected to the switch connected to the Target PC.
Wan2 is the primary connection.
When the WAN2 Ethernet cable connected to RadioA is removed (WAN2 link is broken), failover is successfull to WAN1.
When the WAN2 Ethernet cable connected to RadioA is connected, but RadioB is switched off (WAN2 link is broken, failover does not happen. Failover should happen as the pings are not responded to.
As the physical connection between WAN2 and RadioA is still working, it looks like the RUT995 is failing over when the physical link is broken, and NOT when it does not receive any ping responses.