I read:
https://forum.opnsense.org/index.php?topic=24084.0
Found the linked (and closed) github issue.
I read everything twice and searched again to make sure I didn't miss something obvious :P.
So I think this should be solved and working now? I have several VLANs in their own domain, but my hosts from each of them are registered under the system domain in unbound.
I read in the link above there isn't a setting and should 'just work', but it isn't in my case.
Any ideas please what I am missing?
Thanks!
Sorry! My bad! :-[
Too many things going on! I had cleared the fields in DHCP after making unbound the main resolver at port 53, but I shouldn't have cleared the domain field.