Static client IP - DNS queries unreplied (lots) in connection log.

[Cyanix]

Greetings,

This is what i see when i setup static IP adresses with DNS on the clients (desktop/ Ipad).
As soon as i enter something else than the router IP , i get lots of unreplied queries in my connections.

And this is my system log (last lines)

Nov 12 20:47:38 kernel: nf_conntrack: expectation table full
Nov 12 20:47:46 kernel: net_ratelimit: 5 callbacks suppressed
Nov 12 20:47:46 kernel: nf_conntrack: expectation table full
Nov 12 20:47:46 kernel: nf_conntrack: expectation table full
Nov 12 20:47:46 kernel: nf_conntrack: expectation table full
Nov 12 20:47:47 kernel: nf_conntrack: expectation table full
Nov 12 20:47:47 kernel: nf_conntrack: expectation table full
Nov 12 20:47:47 kernel: nf_conntrack: expectation table full
Nov 12 20:47:47 kernel: nf_conntrack: expectation table full
Nov 12 20:47:47 kernel: nf_conntrack: expectation table full
Nov 12 20:47:47 kernel: nf_conntrack: expectation table full
Nov 12 20:47:47 kernel: nf_conntrack: expectation table full

As soon as i replace the DNS (Cloudflare/OpenDNS/even my own ISP DNS) with the router IP address, everything goes back to normal.

Could someone explain this behavior ?

Router is Rt-AC86U
Firmware Merlin 384.13

Thank you.