My diagnosis is that in vantage's
rbfeeder installation, some files are broken, corrupted or missing. I formed this opinion because dump978-rb is giving proper output on both ports 30978 and 28380. This was confirmed by
commands "nc 127.0.0.1 30978" and "nc 127.0.0.1 28380".
On the other hand rbfeeder, which collects dats from dump978 and dump1090 and passes these to Air Nav Servers complints it cannot connect to port 30978.
In view of above, the best option is to completely
purge rbfeeder and all its files, and then install it fresh.
(1) open file /etc/rbfeeder.ini and from it copy-paste key to you PC Notepad and save it.
(2) Give following command to remove rbfeeder
sudo apt purge rbfeeder
sudo reboot
(3) Make a fresh install of rbfeeder
sudo apt update
sudo apt install rbfeeder
sudo reboot
(4) After reboot check status
sudo systemctl status rbfeeder
https://www.radarbox.com/stations/EXTRPI010179