ftp sessions not being accepted

[Wax]

Hello everyone,

I'm posting this in the Beginners section, because although I have been using cPanel for a couple of years, I'm still a n00b with it.


This morning, I received two eMails from my server, saying that

Service: imap
Notification Type: failed

and

Service: exim
Notification Type: failed

Exactly 5 minutes later, I received another two eMails stating the both services recovered.

All looks good... yet, I have 10 ftp account, of which only 3 of them are able to connect to the server.

These ftp accounts are remote computers, that log in every minute, and upload a small amount of data to their own directory.

Yesterday everything was working fine, yet today (apparently after the "outage"), most account haven't uploaded anything during the entire day.

I already went to WHM (this is a private server, and I have WHM and cPanel), and checked under:
WHM > Security Center > cPHulk Brute Force Protection

Yet there was nothing.
Nothing under blacklist or whitelist.

Any thoughts on what I can do and/or check?

Thank you very much for your help!

 

[Wax]

Hello guys,

Sorry to be such a pest... yet I'm at a loss as to why this is happening.

The remote computers are all in different locations, connected via different ISPs.
So I don't think it has to do with a specific IP set being banned.

Any thoughts on this?
Thank you!