Keep your system time syncronized. Debian

Chrony keeps your system clock syncronized. It syncs clock gently to avoid system clock jumps.
apt-get install chrony

ZyXel и ntp сервер

Выглядит это примерно так:
timesync server 88.201.x.x
time timezone 400
time daylight-saving-time
timesync ntp
На 3012F работает успешно.

ntp клиент cisco

clock timezone MSK 3
clock summer-time MSD recurring last Sun Mar 2:00 last Sun Oct 3:00
ntp clock-period 17207836
ntp server 195.14.x.x
ntp server 195.14.x.x