Endpoint manager for Snom showing time 30 min behind

Using the latest FreePBX 13 distro we have installed EndPoint manager and after reseting the NPT server and the correct timezone the phones using the Commercial EndPointManager are 30 min. behind the date on the PBX and the rest of the phones on the network.

System is using:
FreePBX 13.0.54
Asterisk 11.20.0
SHMZ release 6.6 (Final)

Phones are Snom S-300 firmware version 7

Any suggestions?