Aqui está o temporizador vsftpd-restart.timer
[Unit]
Description=Restart vsftpd daily at 6 AM
After=network.target
[Timer]
Unit=vsftpd-restart.service
OnCalendar=*-*-* 06:00:00
Persistent=true
[Install]
WantedBy=timers.target
Este é o script vsftpd-restart.service
[Unit]
Description=Restart vsftpd daily at 6 AM
After=network.target
[Service]
Type=oneshot
ExecStart=/bin/bash -c 'systemctl stop vsftpd; systemctl start vsftpd'
[Install]
WantedBy=vsftpd-restart.timer
E aqui está o log systemctl vsftpd
Oct 07 06:00:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:00:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:00:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:00:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:00:01 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:01:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:01:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:01:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:01:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:01:01 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:02:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:02:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:02:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:02:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:02:01 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:03:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:03:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:03:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:03:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:03:02 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:04:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:04:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:04:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:04:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:04:01 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:05:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:05:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:05:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:05:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:05:01 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:06:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:06:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:06:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:06:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:06:01 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:07:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:07:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:07:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:07:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:07:01 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:08:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:08:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:08:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:08:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:08:01 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:09:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:09:01 test systemd[1]: vsftpd.service: Deactivated successfully.
Oct 07 06:09:01 test systemd[1]: Stopped vsftpd.service - vsftpd FTP server.
Oct 07 06:09:01 test systemd[1]: Starting vsftpd.service - vsftpd FTP server...
Oct 07 06:09:01 test systemd[1]: Started vsftpd.service - vsftpd FTP server.
Oct 07 06:10:01 test systemd[1]: Stopping vsftpd.service - vsftpd FTP server...
Oct 07 06:10:01 test systemd[1]: vsftpd.service: Deactivated successfully.
O motivo pelo qual sua configuração atual está fazendo com que o serviço vsftpd reinicie a cada minuto das 6:00 às 7:00 da manhã é devido ao temporizador OnCalendar= - -* 06:00:00 ser persistente (Persistent=true). Isso significa que o temporizador tenta "recuperar" eventos perdidos durante o tempo em que o sistema estava desligado, então se o sistema estava desligado às 6 da manhã, isso pode levar a vários gatilhos quando o sistema voltar a ficar online. Isso deve resolver:
vsftpd-restart.timer
E não se esqueça de recarregar com o novo script do timer: