I don't think this is a wiring issue either. As you say it shouldn't be an auto registration problem as this would have registered a long time ago. I would look at the VG Gateway config for this port in CCM. Usually when you see an issue that shows DB Config the problem is in CCM.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.