I cannot get mine to work no matter what.
I installed it before I had my 5G modem router preparing for the 5g router as a backup WAN. The second I connected the LAN cable from that router, the entire internet went down.
I then activated the sim etc - and now the internet returned - but preferred to route traffic to the slower 5g (like 250/25 where my cabled wan is 1000/100 (measured 850/125)).

I have tried:
- interchanging the WAN - WAN2 cables (wan2 = LAN/wan port 1). That made traffic go to the other port but thru the same router
- enabling load balancing using measured bandwidth - that makes traffic distribute like 50%-50% (expected like 75%-25%)
- having online detection to auto (initial choice)
- trying a recurring tip here to set online detection to manual on both wan-ports and ping 8.8.8.8 (dns 0.0.0.0)
- this tip disabling application optimization - or enabling it
- having enable load balancing checked and unchecked

The only way I have successfully managed to make all traffic go to the primary wan-port is to disable the secondary wan.

At best I can bring the traffic to the backup WAN down to like 50% (when enabled)
My primary wan is faster and flat rate, the secondary is on a plan (and only 1/3 of the speed).

I have seen the router table has both routers LAN-IP set to 0.0.0.0 could it be that the traffic is always routed thru the first hit in the routing table?