Wrong Time or Time Zone After Every Reboot — Sync and CMOS Fixes

18 Aug 2026

You correct the clock in Windows 11, restart the computer and discover that the time is wrong again.

The clock may be several hours out, a few minutes slow or reset to a date from months or years ago. You might also notice calendar appointments moving, websites reporting certificate errors or business applications refusing to sign in.

Although these symptoms look similar, they can have very different causes.

The problem may involve:

An incorrect Windows time zone
Automatic time-zone detection choosing the wrong location
The Windows Time service failing to synchronise
A VPN, firewall or network blocking the time source
Windows and Linux interpreting the hardware clock differently
Company policies overriding local settings
A failing CMOS or real-time-clock battery
A laptop that loses its clock when the main battery becomes completely flat
Incorrect firmware or BIOS settings

The quickest way to solve the problem is to identify how the clock becomes wrong rather than repeatedly setting it manually.

First, Identify the Pattern

Before changing anything, restart the computer and note exactly what happens.

The time is wrong by an exact number of hours

For example, the clock is precisely one, five or eight hours ahead or behind, while the minutes remain correct.

This usually points to:

The wrong time zone
Automatic location detection
A daylight-saving configuration issue
A Windows and Linux dual-boot conflict

A failing CMOS battery normally does not produce a neat, repeatable difference of exactly one or several hours.

The time gradually drifts by minutes

If the clock slowly gains or loses time during the day, Windows may not be synchronising correctly with its configured network time source.

Possible causes include:

The Windows Time service
A failed or unreachable time server
A network restriction
A computer that remains offline for long periods
A domain or company time-policy problem
Hardware clock drift

The date returns to an old value

A clock that resets to a manufacturing date, an old year or a default time after the computer has been powered off may indicate a firmware-level problem.

Common warning signs include:

The BIOS date and time are wrong before Windows loads.
The date resets after the computer is unplugged.
BIOS settings are also being forgotten.
A startup warning says that the time or date is not set.
Windows corrects itself only after connecting to the internet.

Incorrect or slowly changing BIOS time and the loss of firmware settings after power-off are recognised symptoms of a depleted CMOS battery. (Dell⁠)

Windows is correct, but Outlook or Teams is wrong

When the taskbar clock is correct but meetings appear at the wrong time, check the time-zone setting within the application or online account.

Outlook can maintain its own calendar time-zone configuration. Teams normally reflects the Windows time zone unless an application-level setting has been changed. (Microsoft Support⁠)

Fix One: Check the Windows 11 Date and Time Settings

Open:

Settings > Time & language > Date & time

Start by reviewing the following controls.

Set time automatically

Turn on:

Set time automatically

This allows Windows to synchronise its clock rather than relying entirely on a manually entered value.

Microsoft’s Windows guidance recommends enabling automatic time and using the synchronisation control under Additional settings when the displayed time is incorrect. (Microsoft Support⁠)

Set time zone automatically

You can also turn on:

Set time zone automatically

This is useful for laptops that regularly travel between regions. However, automatic time-zone detection depends on Windows determining the device’s location correctly.

If Windows repeatedly chooses the wrong zone, turn automatic detection off and select the correct time zone manually.

For a computer used in the United Kingdom, choose:

(UTC+00:00) Dublin, Edinburgh, Lisbon, London

Windows calls the corresponding command-line time-zone ID:

GMT Standard Time

Despite that name, it includes the normal UK daylight-saving changes when configured without disabling DST.

Adjust for daylight saving time automatically

When the selected time zone supports daylight-saving changes, allow Windows to adjust the clock automatically.

Do not manually add or subtract an hour to compensate for British Summer Time. Selecting the proper UK time zone allows Windows to apply the change according to its current time-zone data.

Windows receives updated time-zone and daylight-saving rules through Windows updates. Microsoft advises keeping Windows current where governments or regions change their time rules. (Microsoft Learn⁠)

Select Sync now

Under Additional settings, select:

Sync now

Windows should display a confirmation and the time of the most recent successful synchronisation.

If the time immediately becomes correct but fails again at the next restart, continue through the remaining checks. The underlying problem has not yet been resolved.

Fix Two: Separate the Time from the Time Zone

The clock time and time zone are separate settings.

Suppose the actual UK time is 9:30am.

Windows might contain the correct underlying time but display 4:30am because it has selected a North American time zone. Synchronising again may not help because Windows is already accurately calculating the time for the wrong region.

Check the active zone from an Administrator Command Prompt with:

tzutil /g

For a UK computer, the result should normally be:

GMT Standard Time

To see every time-zone ID recognised by Windows:

tzutil /l

To set the UK time zone manually:

tzutil /s "GMT Standard Time"

Microsoft documents tzutil as the Windows utility for displaying, listing and setting the system time zone. (Microsoft Learn⁠)

Avoid adding _dstoff to the command unless you intentionally need to disable daylight-saving adjustments:

tzutil /s "GMT Standard Time_dstoff"

That modified value prevents the usual summer-time change and is not appropriate for a normal UK computer.

Fix Three: Check Location Services

Automatic time-zone detection may fail when Windows cannot determine the computer’s location.

Open:

Settings > Privacy & security > Location

Check whether Location services is enabled.

If you want Windows to choose the time zone automatically, location access normally needs to be available. A VPN, mobile connection or incorrectly identified internet address can still cause the wrong region to be selected.

When automatic detection repeatedly chooses the wrong location:

Turn Set time zone automatically off.
Select the correct zone manually.
Restart the computer.
Confirm that the manual setting remains in place.

A desktop computer that never leaves one region often gains little from automatic time-zone switching. A fixed manual zone can be more predictable.

Fix Four: Check the Windows Time Service

Windows uses the Windows Time service, also known as W32Time, to maintain and synchronise the system clock.

Open an Administrator Command Prompt and run:

w32tm /query /status

This displays information such as:

The current time source
The last successful synchronisation
The polling interval
Clock offset information

To display only the current source:

w32tm /query /source

To review the wider configuration:

w32tm /query /configuration

Microsoft identifies w32tm as the preferred command-line utility for configuring, monitoring and diagnosing the Windows Time service. (Microsoft Learn⁠)

Restart the service and resynchronise

Run:

net stop w32time

net start w32time

w32tm /resync

A successful resynchronisation should return:

The command completed successfully.

Restart the computer and check the time again.

If the command reports that no time data is available, Windows may not be reaching its configured source or may have an incorrect time-service configuration. Microsoft documents source configuration, name-resolution and network access as areas to investigate when w32tm /resync fails with this message. (Microsoft Learn⁠)

Do not reset a business computer’s time configuration blindly

Avoid copying commands from a random guide that unregister and recreate the Windows Time service.

Commands such as:

w32tm /unregister

w32tm /register

can remove existing configuration. On a domain-joined or managed computer, the time source may be deliberately supplied through Active Directory or Group Policy.

Check with your IT provider before changing the configuration on:

Domain-joined computers
Microsoft Entra-managed devices
Servers
Remote desktops
Virtual machines
Computers controlled through Intune or Group Policy

Fix Five: Check the Internet Connection, VPN and Firewall

Windows cannot synchronise with an online time source when the computer has no usable network connection.

Test the following:

Connect to a stable internet connection.
Temporarily disconnect a VPN.
Select Sync now again.
Restart the Windows Time service.
Check whether security or filtering software is blocking time synchronisation.
Try another trusted network.

Some corporate networks deliberately require computers to synchronise with an internal domain controller rather than a public internet time server.

Do not replace a company time source with time.windows.com without checking the organisation’s configuration first.

Check whether the date is extremely wrong

Secure websites and network authentication depend on certificates and time-limited security information.

When the computer believes it is in the wrong year, websites may fail before Windows has a chance to synchronise normally.

Temporarily set the date and time close to the correct value:

Turn Set time automatically off.
Select Change beside the manual date and time control.
Enter an approximately correct date and time.
Reconnect to the internet.
Turn automatic time back on.
Select Sync now.

This is only a recovery step. If the computer forgets the date again after power-off, investigate the firmware clock and CMOS battery.

Fix Six: Check for Windows Updates

Time-zone definitions can change when governments alter daylight-saving rules or time-zone boundaries.

Open:

Settings > Windows Update

Install available updates and restart the computer.

Microsoft states that Windows updates its stored time-zone information when new time-zone updates become available. (Microsoft Learn⁠)

Updates may also include:

Firmware improvements
Chipset drivers
Power-management changes
Reliability fixes
Manufacturer-specific real-time-clock corrections

Check Advanced options > Optional updates for relevant firmware or chipset updates, but use the computer manufacturer’s support service when you are unsure which firmware applies.

Fix Seven: Check the BIOS or UEFI Clock

The firmware clock runs independently of Windows and maintains the date and time while the operating system is not running.

To test it:

Restart the computer.
Enter the BIOS or UEFI setup screen.
Check the displayed date and time.
Correct it if necessary.
Save the settings.
Shut the computer down completely.
Leave it powered off for several hours or overnight.
Re-enter the firmware setup before Windows loads.

The key used to enter setup varies by manufacturer. Common options include:

F2
Delete
Esc
F10
F12

Use the manufacturer’s instructions for the exact computer.

What the result means

The firmware time remains correct

The battery and real-time clock are probably retaining their settings.

Focus on:

The Windows time zone
Automatic location
Windows Time synchronisation
Dual-boot configuration
Company policies
Virtualisation

The firmware time is wrong again

If the BIOS or UEFI clock has reset before Windows starts, the cause is below the Windows operating system.

Possible causes include:

A depleted CMOS or RTC battery
A fully discharged main battery on a model without a separate CMOS battery
A firmware fault
A motherboard problem
A recent BIOS or CMOS reset

Windows commands cannot permanently correct a hardware clock that loses power whenever the computer is switched off.

Fix Eight: Recognise a Failing CMOS Battery

Traditional desktop computers often use a small coin-cell battery to preserve the real-time clock and selected firmware settings while the computer is unplugged.

Common symptoms include:

The date resets after every full shutdown.
The time becomes wrong after unplugging the computer.
The BIOS forgets customised settings.
Boot-device settings return to defaults.
A startup warning says the time or date is not set.
Windows becomes correct only after internet synchronisation.
The issue is worse after the computer has been unused for several days.

Dell identifies an incorrect or slow BIOS date and time and the loss of BIOS settings when powered off as common symptoms of CMOS battery failure. (Dell⁠)

Not every computer uses a standard CR2032 battery

Many desktop motherboards use a replaceable CR2032 coin cell, but you should not assume that every computer does.

A laptop may use:

A wrapped coin-cell battery with a cable
A rechargeable RTC battery
A soldered component
The main laptop battery
No separate CMOS battery at all

Dell documents current laptop models where the real-time clock resets when the main battery is fully drained because those systems do not contain a separate CMOS battery. (Dell⁠)

Check the service manual for the exact model before buying or attempting to replace anything.

Before Replacing a CMOS or RTC Battery

Changing the battery is straightforward on some desktop computers and significantly more involved on modern laptops.

Back up the BitLocker recovery key

Firmware or hardware changes can occasionally trigger a BitLocker recovery prompt.

Make sure you can retrieve the recovery key before opening the computer or changing firmware settings. Microsoft explains that hardware or firmware changes can cause BitLocker to request the recovery key during startup. (Microsoft Support⁠)

Record important BIOS settings

Take photographs or notes of relevant settings, including:

Boot order
Storage-controller mode
Secure Boot state
Virtualisation options
Fan or performance settings
Date and time
Custom security settings

A depleted or removed battery may cause these values to return to their defaults.

Do not change settings that you do not understand. An incorrect storage or boot setting can prevent Windows from starting.

Use the manufacturer’s service manual

Before opening the computer:

Shut Windows down.
Disconnect the mains adapter.
Disconnect external devices.
Follow the model-specific battery-disconnection procedure.
Use suitable anti-static precautions.
Confirm the battery type and polarity.
Replace it only with the specified equivalent.
Reassemble the device before reconnecting power.

Laptop batteries, internal cables and motherboard connectors can be easily damaged.

For a sealed or business-critical laptop, professional replacement is usually safer.

Fix Nine: Consider a Dual-Boot Clock Conflict

A predictable time difference after switching between Windows and Linux often comes from the way the two operating systems interpret the hardware real-time clock.

Linux systems commonly keep the hardware clock in Coordinated Universal Time, while Windows traditionally interprets it as local time. The result can be a clock that shifts by the local UTC offset whenever the other operating system updates the RTC. (Microsoft Learn⁠)

For a UK user, the clock may appear correct during winter but shift by one hour during British Summer Time.

There are two broad solutions:

Configure Linux to treat the hardware clock as local time.
Configure Windows to treat the hardware clock as UTC.

The best approach depends on the Linux distribution, encryption, virtualisation and other operating systems installed.

Windows UTC Registry method

Microsoft documents the RealTimeIsUniversal value in some Windows deployment scenarios:

Set-ItemProperty `

-Path "HKLM:\SYSTEM\CurrentControlSet\Control\TimeZoneInformation" `

-Name "RealTimeIsUniversal" `

-Value 1 `

-Type DWord `

-Force

This changes the way Windows interprets the hardware clock. Microsoft uses this setting in official guidance for preparing certain Windows virtual-machine images. (Microsoft Learn⁠)

Do not apply it merely because the time is wrong once.

Use it only when you have confirmed a genuine UTC-versus-local-time conflict and understand how every installed operating system manages the RTC.

After changing the convention, set the correct time in one operating system, restart both systems and test across several boots.

Fix Ten: Check for Software That Changes the Time Zone

Some applications and management tools can alter the time or time zone at sign-in or startup.

Possible examples include:

VPN software
Remote-access platforms
Virtual-machine software
Hotel or travel applications
Company login scripts
Group Policy
Microsoft Intune policies
Endpoint-management agents
Location or geolocation tools
Dual-boot utilities
Timekeeping or laboratory software

A useful test is to disconnect from the VPN and perform a clean restart.

If the correct time zone changes only after the company software connects, report the pattern to IT rather than repeatedly correcting the clock.

Check Task Scheduler

Open:

taskschd.msc

Review:

Task Scheduler Library

> Microsoft

> Windows

> Time Synchronization

Do not disable built-in tasks without a clear reason. Instead, check their history and status to determine whether synchronisation is running or failing.

Microsoft notes that the Windows Time service can be triggered by scheduled time-synchronisation tasks on workgroup computers. (Microsoft Learn⁠)

Fix Eleven: Virtual Machines Need Their Own Time Strategy

A Windows virtual machine may receive time from:

Its virtual hardware clock
The host computer
The Windows Time service
A domain controller
A cloud-platform integration service

When more than one source attempts to correct the clock, the time may jump repeatedly.

Do not assume that public NTP synchronisation is the correct solution inside every virtual machine.

For business or cloud environments, check the guidance for:

Hyper-V
VMware
Azure
Windows 365
Azure Virtual Desktop
The organisation’s domain

Microsoft explains that Azure Windows virtual machines may use several time sources, including the host and Windows Time, depending on the machine’s role and configuration. (Microsoft Learn⁠)

Why the Correct Time Matters

An incorrect clock is not merely cosmetic.

It can affect:

Microsoft 365 and cloud sign-ins
Security certificates
Multi-factor authentication
Windows Update
Email timestamps
Teams and Outlook meetings
File synchronisation
Backup schedules
Audit logs
Domain authentication
Scheduled tasks
Software licences

Microsoft specifically recommends verifying the time and time zone when troubleshooting Windows Update because incorrect values can interfere with the update process. (Microsoft Support⁠)

On a business network, authentication protocols and security logs depend on computers maintaining a consistent view of time. Avoid manually forcing a company device to an independent time source without understanding the domain configuration.

A Sensible Troubleshooting Order

When Windows 11 shows the wrong time after every reboot:

Note whether the error is a precise number of hours, gradual drift or a complete date reset.
Open Settings > Time & language > Date & time.
Enable Set time automatically.
Select the correct time zone.
Turn automatic time-zone detection off if it repeatedly chooses the wrong location.
Select Sync now.
Check the current zone with tzutil /g.
Check the Windows Time source with w32tm /query /source.
Restart the Windows Time service and run w32tm /resync.
Test without a VPN or restricted network.
Install Windows, firmware and chipset updates.
Check the time directly in BIOS or UEFI.
Leave the computer powered off and test whether the firmware retains the time.
Check for a dual-boot UTC-versus-local-time conflict.
Review company policies, scheduled tasks and virtual-machine settings.
Back up the BitLocker key before firmware or hardware work.
Replace the CMOS or RTC battery only according to the manufacturer’s service instructions.

Get Help Fixing Repeated Time and Date Problems

A clock that is wrong by a few hours normally points to a time-zone or dual-boot configuration issue. A date that resets whenever the computer loses power is more likely to involve the firmware clock, main battery or CMOS battery.

Hamilton Group can diagnose Windows 11 time synchronisation, repair Windows Time configuration, investigate domain and Microsoft 365 authentication problems and replace failing desktop or laptop RTC batteries where appropriate.

We can also help businesses correct time-source policies across managed Windows computers, servers, remote desktops and virtual machines.

Call 0330 043 0069, book a meeting with one of our experts or visit hgmssp.com for practical help keeping your Windows devices accurate and reliable.