Dual WAN Loadbalancer: cannot resolve DNS

[Gatto]

Hello,
my configuration consists of:

1 DNSMasq
2 WAN (coming from: 192.168.1.254 and 192.168.4.1) ->
1 LoadBalancer gateway (attachment 2) ->
Firewall rules to route the traffic inside my LAN (IP: 192.168.3.1) + DNS Firewall rule (attachment 1)

When I activate the rule (LAN -> LoadBalancer) to the whole LAN Network, the system stops resolving DNS.
If I activate the same rule only to my computer IP address everything works smoothly.

I tried to log things but I can't see anything strange, probably because I am just ignorant.
If it helps this is my machine: https://www.applianceshop.eu/dec2630-opnsense-a10-quad-core-ssd-rack-gen2.html

[Gatto]

This system status (attachment) will help too I suppose

[franco]

What are your DNS server settings under System: Settings: General?


Cheers,
Franco

[Gatto]

What are your DNS server settings under System: Settings: General?


Cheers,
Franco

You can see my attachment

[franco]

Yes, here we are: you cannot use the same DNS IP for more than one gateway.


Cheers,
Franco

[Gatto]

Yes, here we are: you cannot use the same DNS IP for more than one gateway.


Cheers,
Franco

Okay, you can see by my attachment that I have changed DNS.
This seems to work, it took 10 minutes to propagate but it's working now.
I will reply again if something breaks.
Thank you! Get your karma!

[franco]

Likewise, happy it works.

[Gatto]

Okay, this is not working.
I can't really explain what is the pattern but the connection comes and goes in an apparently random way.
Logs are green.

[franco]

Can you please elaborate? I think the DNS is indeed fixed persistently so we're on to the next one...

[Gatto]

The connection stays alive for like 5 to 10 minutes then it drops for 2-3 minutes then it comes back.
The gateways are stable, this is not a ISP problem.

[Gatto]

I think it is a DNS problem.
If I apply the loadbalancer rule just to my pc everything works fine.
I think it is probably related to the rule that catches any traffic from LAN net (even my opnsense traffic I suppose)

[Gatto]

Yep, I confirm it.
I left a ping console pinging 8.8.8.8 and another console curling amazon.com.
The ping never stops, the amazon.com curl resolves for some time then stops then start resolving again.