Francis,
Its not entirely clear where you get your timestamps from or what is lagging 17 hours behind so I am assuming the following.
- You use the RTC of the WP8548.
- WP stores data and does not transmit it real time, when it stores it you time stamp it using this RTC time.
- The server then takes the data and displays it as per the received time stamped information?
Is the above correct?
I am not sure what would cause a 17 hour delay, it would need more testing but only thing that might influence the RTC other than losing power would be the NITZ message coming from the network, or the lack of one. Some networks support it others do not. If you have no other guaranteed mechanism of pushing time to the server such as using an NTP server then I would either fire up the GNSS ont the unit to get the time from GPS or send an SMS with status reports turned on then you can get the time from the SMS service centre.
Regards
Matt