Two weeks are passed, the previous one, is reported here.
So, after this time, I know that the issues that NS was having from some months ago where caused by the savage antivirus we use, not a bad thing (but worse 
), mental note to remember that security tools can create issues in a local and weak network: Deny Of Service galore.
Using some filters for the antivirus ‘fix’ the thing.
Maybe avast treat/see the file system in different way on Nethserver (samba shares) than in windows (shared folders) 
because I don’t see the old file server stressed by the scanning (right now). Ah some users report slow response from time to time on the network.
When our new NAS arrive, the issue can reappear but in another device.
Time to learn how to scan our network traffic, maybe with wire shark or some tool related. Any ideas?
Thanks and regards.