I am using Raspberry PI Model B with Raspbian, installed by NOOBS, upgraded to the latest version. The NTP server is automatically started in the boot process.

When I boot my RPI, the time is always wrong — about 15 minutes in the past. Even if I wait for several hours, it's incorrect.

I run

    /etc/init.d/ntp restart

manually and it sets the correct time within seconds, sometimes it needs two restarts.

I define several servers in the ntp.conf:

     server ntp1.t-online.de iburst prefer

     server 0.de.pool.ntp.org iburst
     server 1.de.pool.ntp.org iburst
     server 2.de.pool.ntp.org iburst
     server 3.de.pool.ntp.org iburst
     ...

Does anyone have an idea how to fix this? Thanks in advance!