Dietpi | Raspberry-pi-4 time-sync issues on nodejs and reactjs

So I am running dietpi on rasp pi 4
and it is running a nodejs server and react server
the issue is that when it restarts,
if there is internet connected, my application running in kiosk mode will show correct time
and if there is no internet, it shows wrong time

what to
if i have to setup an RTC, how to do that
and is there any way without RTC

This is to be expected, as the time cannot be synchronized without a network connection. At least the connection to a local time server must be available.

Google might be your friend Adding a Real Time Clock (RTC) to the Raspberry Pi - Pi My Life Up
Or some similar topic on our GitHub HWClock support · Issue #3393 · MichaIng/DietPi · GitHub

don’t think so