[briHass]

The gateway/router should be the time source. DHCP has an option to provide the time server (NTP) - option 42, and most decent devices or OSS/DIY router software (OpenWRT, opnSense) will support that as well as being the local time server.

[BenjiWiebe]

That does require being connected to the AP though.

[ComputerGuru]

The counterpoint to that is you aren't trusting any random wifi signal strong enough to reach your device to be telling the truth about the time!