Strange problem with FTP and fail2ban

I’m running Hestia CP on 2 vservers (Debian 10) since a few weeks. Both have the same problem (but on different times):

After a few hours (sometime days) the severs won’t let me connect via FTP. At the beginning I did a full restart and I can connect again, but now I found out that only fail2ban needs to get restartet.
I’m not blacklisted (a restart didn’t clear the blacklist) and the problem also apears if I try to connect from the server itself (FTP-Connection with PHP script to localhost).

Any solution ideas? (I don’t want do deactivate fail2ban)

UPDATE: The Problem seems to be bigger. fail2ban restart doesn’t help anymore. Now I have to completely stop it. (Still not blacklisted)

Check the /var/log/auth.log and /var/log/vsftpd.log

When F2B restarts the old banned are not revoked as they are saved in “Hestia”

the logs are ok, but:

When i try to connect with Filezilla, i get a critical error.
fail2ban.log: not logged (ok, not banned)
auth.log: not logged
vsftpd.log: not logged