Websites think my system time is 7 hours ahead despite correct time on laptop

[wilberfan]

I’m in the Pacific (Daylight) Zone (California), and both the BIOS system time, and the system time inside Manjaro are set and display properly. But various websites will timestamp a post/entry as 7 hours ahead (UTC, I think?) Network sync is installed and running.

For example, here’s a screen grab of an entry I just made on a food diary website. I made it at local time 1030 but you can see it’s reporting 1730 (5:30pm).

It’s not just this website either. A recent post on Discord was 7 hours ahead as well.

One possible factor (although I don’t understand how it would be the case) is that this is a dual-boot laptop with Win 10 installed. I don’t boot into it very often (why bother when you have Manjaro installed!) but the system clocks display the correct time there as they do in Manjaro.

[edit] The same entry to the same website when booted into Windows has the identical 7-hours-ahead timestamp–so it must be hardware related??

[Teo]

You correctly identified the problem (Windows). Type timedatectl in a terminal. Do you see a big fat warning at the end? If yes, correct it with

timedatectl -set-local-rtc 0

Adjust the clock if necessary. Reboot in windows. Open regedit.exe and add dword value in

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TimeZoneInformation

RealTimeIsUniversal = 1

Reboot, adjust clock in bios once more, let it sync and you should be fixed.

[wilberfan]

Brilliant. I’d had dual-boot systems before, and had set that registry key–but for some reason I didn’t in this time.

Everything seems copacetic now! Thanks!

[edit] Spoke too soon (see below)

[wilberfan]

I spoke too soon. Websites are again reporting my posts as UTC. I went thru the process again–even adding a line to the Win 10 registry: (from here)

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient]
“Enabled”=dword:00000000

$ timedatectl is correctly reporting Local time as PDT, Universal time: as UTC, and RTC the same as UTC. BIOS time is UTC.

[wilberfan]

It turns out that timestamps are incorrect ONLY IF I USE FIREFOX. Brave, Vivialdi report the correct time.

I found this, here:

Note that when privacy.resistFingerprinting is enabled you are in the UTC time zone.
Screen/window sizes are spoofed as well and site specific zoom is disabled and the user agent is spoofed to the current ESR release among other changes.

[cscs]

I use
/etc/NetworkManager/dispatcher.d/09-timezone

#!/bin/sh
case "$2" in
    connectivity-change)
        timedatectl set-timezone "$(curl --fail https://ipapi.co/timezone)"
    ;;
esac