On Windows, timevar2 is the number of seconds since the client was opened.
On Linux/Mac, it is the number of seconds since 1st January 1970 (see
UNIX time).
On the serverside, timevar2 is representing the time in France I guess, while on the clientside on Linux/Mac, it is representing the local timezone.
If it is important that your time is the same for every user, then run your calculations serverside, since Linux/Mac users will get time relevant to their timezone, and Windows users will get something altogether completely different.