LoRaWAN time synch Lora E5 mini

I set one Rpi with wm1302 and TTN console, and one Lora E5 mini end device.
i manage to run and get uplink and downlink from the console
but when i try to set time Synchronization with AT command
i mannage just to time synch manualy with AT+RTC="year-month-day hour ", if i reset the Lora e5 device it come back to starting point 2000-01-01 00:xx:xx.
if i try to set direcly from the server with AT+LW=DTR i get +LW: DTR but no data.
my device is set with class C and Lora version 1.0.3.

someone can point me how to get this time synch data in the end device when it join to the LoRa network?