Thank you for you reply.
Yes, I checked fail2ban log, no issue. the IP server is in the whitelist. I also stopped the fail2ban server yesterday. But the problem is still there.
It seems that there is a software in the middle that block the requests, but why it unlock all with an ftp request!
From yesterday all following service are ramdomly unreachable (for timeout of the request):
- plesk panel (port 8443)
- ssh service
- all domains
(The Ping command works. )
But FTP works, and if I access via FTP (in one of domain on the server ) the above-mentioned services returning...