Also note that the actual output provided initially showed that the connection was actually successful / the feed wasn’t down:
feed.community.greenbone.net [45.135.106.143] 873 (rsync) open
@RSYNCD: 31.0
Greenbone community feed server - http://feed.community.greenbone.net/
This service is hosted by Greenbone Networks - http://www.greenbone.net/
All transactions are logged.
If you have any questions, please use the Greenbone community portal.
See https://community.greenbone.net for details.
By using this service you agree to our terms and conditions.
Only one sync per time, otherwise the source ip will be temporarily blocked.