Cannot connect to host updater.home-assistant.io:443

Hi,
I’ve just re-installed Home Assistant on my Raspberry Pi 4B 4GB.
When I start it, I get the following error message in the log

2020-09-12 14:20:23 ERROR (MainThread) [homeassistant.components.updater] Error requesting Home Assistant update data: Cannot connect to host updater.home-assistant.io:443 ssl:True [SSLCertVerificationError: (1, ‘[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: certificate is not yet valid (_ssl.c:1124)’)]

I read some other people having a similar error message. The reason there was, that the address got blocked by their PiHole.
But I don’t use PiHole (nor have I ever installed it).

Also strange is, that the date of the error log entry is set to “2020-09-12”.

Does anyone have an idea what can I do about this?

Thank you.

When I try to get the url via curl:

curl https://updater.home-assistant.io/

I get the following error:

curl: (60) SSL certificate problem: certificate is not yet valid
More detaisl here: https://curl.haxx.se/docs/sslcerts.html

curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.

This seems to be related to the wrong system time.
So the real question here is, how to change the system time.

I installed HomeAssistant via Docker now, which runs perfectly.