Hello everyone
I recently updated my RB941-2nD to V7.3.1 from V6.49, with the same config when I connect to a VPN L2TP/PPTP from the increase in ping latency on network devices (the one that I route it's traffic inside the VPN) I know that the device traffic it's routing correctly but the mikrotik router is no longer working as a DNS sever and all the DNS requests are failing and no DNS queries from client is resolved unless I use an external DNS server like 1.1.1.1 on the device (client) network adapter. (even adding 1.1.1.1 to router DNS server is not helping)
My configurations:

If you mean that 10.10.5.134 can't access router, then it's the latest change, routing marks now have priority over everything. Adding dst-address-type=!local to your two mangle rules should fix it.

I did add those but no change.
But cause v7.3.1 was a bit heavy for RB941-2nD, I end up going back to v6.48.6.

Yes, this model didn't have too many resources to spare even with v6. But if I understood correctly how exactly it didn't work, the change should have helped. Btw, you shouldn't need those mangle rules for 10.10.5.134 at all, because it's already covered by routing rules for whole 10.10.5.0/24.

Yeah there is like 6MB RAM left although for some reason it was around 8MB with 7.3.1 but the CPU is way less busy.
I think that was there because I was wanted only 10.10.5.134 to have access to the VPN, although I'm not very familiar with V7 and the way it's route things.