What configuration possibillities does my RBR850 (still) have?

I have scoured these forums and internett to see what the options are forg my RBR850 if i want to do something that is not configurable in the GUI. My specific case is that i want to edit DNS records in the router so that i can point to a server on my local network with a better name. I also want to have subdomain for different services running on said server but on different ports (gonna have an ngixproxy for this, but i need to get the sub-domains to point to the right place first)

So what is the most best way to do this? Is the access even possible? I have gotten my hopes up with the debug-site and telnet-enabling from this, and then got them squased again when it was unavailble, Hopes have risen again with the possibillity with custom firmwares, but so far it seems that RBR850 is not supported by voxel.

I also thought i saw that telnet is now complete shutoff for RBR850?

Can someone give me summary of the options, or even if there _is_ any options left, that i have to configure my Orbi? Or have Netgear botched EVERYTHING with this expensive device and not let us actually use it properly?

(Dont get me started on the other dns-troubles i have read about)

Firmware: V3.2.16.22_1.4.9