I'm facing an issue while configuring a DNS forwarder.
In my configuration, the upstream DNS server is also the upstream gateway.

Let's say that :

• LAN is 192.168.0.0/24
• WAN is 192.168.255.0/24. (private network is not a mistake, this is an interconnection to the upstream router). .253 is pfsense, .254 is the upstream router.
• An upstream gateway is declared on WAN interface with 192.168.255.254
• The upstream router also privide the DNS service (And I have to use it for this WAN interface.
  It is related to MPTCP bypass function on the upstream router. No choice)
• (of course nat is disabled on pfsense)

So in "general config" I try to add 192.168.255.254 as DNS forwarder, and make it use the gateway (which has the same IP)

It gives the following error :

A gateway can not be assigned to DNS '192.168.255.254' server which is on a directly connected network.

I can't figure out if it's a feature or a bug. What would be the point of such limitation ?

Please note that everything is working well if I use an online DNS like 1.1.1.1 or 8.8.8.8 except that I will have some MPTCP limitation if I can't use 192.168.255.254 instead.
I'm using version 2.4.5-RELEASE-p1.

Does anybody have an explanation (or a solution) ?

Thanks