Seamless failover

Hello dave12
I’m trying to setup almost exactly what you have mentioned here. WAN1 is a PPPoE connection (Public IP- Dynamic) that works over ethernet and WAN2 is an android USB hotspot (Private IP - NAT )
My preferred WAN is WAN1 and I want to failover when the PPPoE interface is down and also in situations when there is a specific packet loss detected for an address on the internet (e.g. >3% loss to 8.8.8.8 )
After WAN1 has no more packet loss/ is up, I want it to switch back to WAN1
Could you please help me with the configuration that you’ve done on your device to understand how I need to achieve this?