All our SNOM phones are showing 2 hours behind, yealink phones for example are OK, all working with our timezone and NTP server.
Can you please try the latest version 188.8.131.52?
I created ticket #19149 for this issue so that we can have a better look at your settings and logs.
Posting here the solution we found via the ticket.
This can prevent the NTP system from setting the time correctly.