Raspberry Pi OS Time Source / NTP

Check current config

timedatectl 

Local time: Wed 2021-07-07 19:17:53 UTC
Universal time: Wed 2021-07-07 19:17:53 UTC
RTC time: n/a
Time zone: Etc/UTC (UTC, +0000)
System clock synchronized: no
NTP service: active
RTC in local TZ: no

Change time source / NTP

sudo nano /etc/systemd/timesyncd.conf

[Time]
#NTP=
FallbackNTP=192.168.1.200