@Hubzilla Support Forum
What's interesting is that in boot.php the value NULL seems to be passed as database host to the dba_driver constructor.

Yeah, that's quite wierd... you did quote the addresses?

In any case, as mentioned in the matrix channel, I don't think it will work even if the address is set correctly. Hubzilla assumes that if it finds a colon in the server address, it's a unix socket.

You could try adding a hostname for the db server instead.