You said “The NTP server doesn’t provide any information about the timezone” — yes, of course, that’s why I said “The time is calculated using two pieces of information: the NTP time (which is UTC+0 time) and the time zone.
Your time zone looks fine: 56 means UTC+2, which I assume is the correct time zone for your location. If time zone is correct, then the only thing I can think of would be NTP is getting an incorrect UTC+0 time for some reason. Go to Edit Options -> Advanced, NTP Server IP, what’s the IP set there? If you have firmware 2.1.9(3), you can set it to 0.0.0.0, which will make it use the default pool.ntp.org. Otherwise if there is a valid NTP IP address, it will use that server.