OK, I will check. I don’t think it should have anything to do with static ip vs. DHCP — the only reason for time being invalid would be NTP time sync fails.
By the way, even with DHCP, you can still set a fixed IP, by going to your router’s configuration page, and set a DHCP reservation for the device (basically binding a fixed IP to its MAC address). This is effectively static IP, but managed using the router.