Thats where vague comes along … you can litterally search for ANY know value, and browse a bit.
Connections issues ? Look for your own IP or the username entered.
FTP issues ? Look for FTP
Mail issues ? Look smtp, imap, sogo or the like.
If you apply your non-nethserver-specific knowledge to the topics, you will easily get there. The manual helps a lot too. It’s mostly up to date, and a wealth of ‘gotcha’ information, instead of exhaustive lists with features you will likely never use.