Is there any other (GUI) DNS/DHCP server available in OMV3?
Not that I know of.
Not having any kind of DNS/DHCP server in OMV 3 would be really a show-stopper for me and a reason to either remain on OMV2 or switch to another NAS OS.
I don't understand why a DNS/DHCP server has to be on a NAS let alone have to have a plugin. Two of six commercial NASes I looked at have this ability.
Of course one could always configure it manually.
There are dockers out there that have a web interface and we have a docker plugin. Another option...
But there's already a lot that has to be configured manually (i.e. no more Virtualbox-gui)
Well since there is a virtualbox gui (plugin works as far as I know), what else has to be manually configured?