Multi WAN and port forwarding

ok, thanks for your help.
In production there is only ether-11-LAN in use.
But, at the moment I connect my self direct to ether-10-INT.

I have a hex router I created 3 DSTnat for 3 servers I want it to be a priority between nat , if one of the servers does not answer the request, it will be automatically transferred to the next net I checked the priority nat method and it didn’t work
Does anyone suggest a better method?

The automation has to be on the user side, the router cannot do that in regular programming.

for this kind of incoming load balancing I would setup a proxy like an IIS with ARR and config a server farm.
Here you could specify the loadbalancing, health test and so on.

regards
Oliver