today i found the solution. i have had to do the deep sleep at the second core of my esp. there only the wlan connection is executed. so i putted in the deepsleep and now it works!
thanks for your help ESP_Sprit!

Maybe someone can explain why it is like that?

yes, i try it today!

I also tried an other rtc library now ..with the same result (RTClib)
so the problem must be somewhere else..

what i thought .. is that i set the clock in the setup() 10 minuts less .. so it would set the clock after the deepsleep back .. but i do not think this is the best solution

i really don´t understand why this happens, because at daytime i measured a offset of eg. max +3 seconds over 12 hours (while controller is running). I know its also not a good offset but wouldn´t be as bad because in the final program i do a sync with the ntpServer (but it´s not always possible to ...

thanks for your replay! my setup: external RTC 1307 on the controller. No alarm function on hardware side available, therefore the ESP should use the internal timer (RTC from the controller) and should than go into the DeepSleep when waking up, the clock should be used again by the external RTC. The...

i tired it like it is described in this article on gidhub https://github.com/espressif/arduino-esp32/issues/1077 i stoped wifi and bluetooth on the first core of the ESP with the commands in the loop() WiFi.mode(WIFI_OFF); btStop(); but after the lines below there is only a short connection and disc...

Has anyone already noticed a similar problem?
i leave my esp32 for 9 hours in the DeepSleep and after waking up (with its timer) is a time offset of the RTC of +10 minutes and a few seconds.

i have a rtc clock which works fine before switching in DeepSleep (no offset).