8 reasons why Internet time sync doesn’t work in Windows 10 (and how to fix it)

Windows shows the wrong time or refuses to sync with Internet servers because the system can’t reach or trust a time source, the Windows Time service is misconfigured or stopped, or local settings (time zone, firewall, policies, hardware clock) override synchronization. If you’re seeing that Internet time sync doesn’t work, this article explains the eight most common causes and gives exact, step-by-step fixes so you can get Windows 10 syncing reliably again.

You’ll learn how to check and restart the Windows Time service, change NTP servers, open firewall ports, fix Group Policy and registry issues, diagnose network or hardware problems, and run the commands that force a resync.

Key Takeaway

The single most effective fix is to run the Windows Time service correctly and force a resync from an admin Command Prompt:

1. ensure Windows Time (w32time) is set to Automatic and running,
2. configure a reliable NTP server, then
3. run w32tm /resync (or unregister/register w32time if needed).
   This solves most Internet time sync failures.

Quick Fix Guide

Quick Fix Guide

Reason for the Problem	Quick Solution
Windows Time service is stopped or disabled	Set Windows Time (w32time) to Automatic, start the service, and run w32tm /resync.
Incorrect time zone or daylight settings	Set the correct Time zone in Settings > Time & Language and disable automatic time zone if needed.
Firewall or router blocking NTP (UDP 123)	Allow UDP port 123 in Windows Firewall and on your router.
Wrong or unreachable NTP server	Switch to a known server (e.g., time.windows.com or pool.ntp.org) and test with w32tm /stripchart.
Network issues, captive portal, or proxy	Ensure full Internet access (bypass captive portal), disable proxy during tests, and confirm DNS resolution.
Group Policy / domain settings override sync	Check gpedit.msc / domain policy for time settings; set Type to NTP if standalone.
CMOS/BIOS battery failing (clock resets)	Replace the motherboard battery (CR2032) if BIOS time resets on power off.
Corrupted Windows Time configuration	Re-register the service: w32tm /unregister then w32tm /register, restart service, and resync.

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Detailed Fixes for “Internet time sync doesn’t work in Windows 10”

1. Windows Time service is stopped or disabled

Why this causes the problem:
Windows relies on the Windows Time service (w32time) to handle NTP synchronization. If it’s stopped or disabled, no automatic or manual sync will work.

Step-by-step solution:

1. Open Start → type services.msc → press Enter.
2. Find Windows Time in the list.
3. Right-click → Properties. Set Startup type to Automatic (or Automatic (Delayed Start)).
4. Click Start (if not running) then OK.
5. Open an elevated Command Prompt (right-click Command Prompt → Run as administrator).
6. Run:
   • sc query w32time (to verify status)
   • net start w32time (starts the service)
   • w32tm /resync /nowait (force immediate resync)
     Notes:

• If you see an error about the service not being registered, see section 8 (re-register).

2. Incorrect time zone or daylight settings

Why this causes the problem:
If the time zone is wrong, the clock may appear incorrect even though synchronization works. Also, automatic time zone changes (location services) can cause confusion.

Step-by-step solution:

1. Open Settings → Time & Language → Date & time.
2. Ensure Set time automatically is On and Set time zone automatically is either On (if you move locations) or Off and manually select the correct Time zone.
3. If daylight saving adjustments are wrong, toggle Adjust for daylight saving time automatically.
4. After changing, run w32tm /resync in an elevated Command Prompt.

Tip:

• If your PC is in a domain, domain controller time may be authoritative—coordinate time zone settings across the domain.

3. Firewall or router blocking NTP (UDP 123)

Why this causes the problem:
NTP uses UDP port 123. If Windows Firewall or a network device blocks that, the client can’t reach NTP servers.

Step-by-step solution (Windows Firewall):

1. Open Control Panel → Windows Defender Firewall → Advanced settings.
2. Click Inbound Rules → New Rule….
3. Choose Port → UDP, enter 123 in Specific local ports → Allow the connection → apply to appropriate profiles → name it Allow NTP UDP 123 → Finish.
4. Repeat under Outbound Rules if your policy blocks outbound UDP.
5. Test with w32tm /stripchart /computer:time.windows.com /dataonly /samples:5 (elevated CMD).

Step-by-step solution (router):

• On home routers, forward/allow UDP 123 or ensure NAT/firewall rules permit outbound UDP 123 to the Internet. Consult your router manual.

Note:

• Corporate firewalls may block NTP; speak with IT to allow a managed NTP server.

4. Wrong or unreachable NTP server

Why this causes the problem:
If the configured server is down, mistyped, or blocked, sync will fail. Default servers can be unreliable if blocked.

Step-by-step solution:

1. In an elevated Command Prompt, check current peers:
   • w32tm /query /peers
   • w32tm /query /status
2. To set a reliable server, run:
   • w32tm /config /manualpeerlist:”time.windows.com,0x9 pool.ntp.org,0x9″ /syncfromflags:MANUAL /reliable:no /update
3. Restart Windows Time:
   • net stop w32time && net start w32time
4. Force resync:
   • w32tm /resync /rediscover
5. Verify with:
   • w32tm /query /status
   • w32tm /stripchart /computer:pool.ntp.org /dataonly /samples:5

Tip:

• The 0x9 flag uses special poll bits (NTP client mode) and can help with reachability. Substitute servers if a particular one is blocked.

5. Network issues, captive portal, or proxy

Why this causes the problem:
If your PC isn’t actually connected to the Internet (captive portal like a Wi‑Fi login page) or uses an HTTP proxy for web traffic, NTP may be blocked because it uses UDP.

Step-by-step solution:

1. Confirm Internet access by opening a browser and loading a few websites.
2. If a captive portal appears (hotel/coffee shop), complete the login first.
3. Temporarily disable proxy: Settings > Network & Internet > Proxy → turn off Automatically detect settings and any manual proxy to test.
4. Try resync: w32tm /resync.
5. If your network requires a proxy and blocks UDP, you’ll need to use a local NTP server inside the network (ask network admin).

Tip:

• Many corporate networks block UDP 123 on guest networks; use company-approved NTP servers.

6. Group Policy or domain settings override sync

Why this causes the problem:
Domain-joined computers typically sync time with the domain hierarchy (DCs). Group Policy or domain settings can force clients to use NT5DS (domain controller) instead of Internet NTP.

Step-by-step solution:

1. If joined to a domain, ask IT—domain controllers should provide time.
2. Check local policy: Run gpedit.msc → Computer Configuration > Administrative Templates > System > Windows Time Service > Time Providers.
3. Ensure relevant policies (Configure Windows NTP Client) are not incorrectly set. If you must force Internet NTP on a standalone PC, set Type to NTP using:
   • w32tm /config /syncfromflags:MANUAL /manualpeerlist:”time.windows.com” /update
4. If domain policy is enforced, change must be done at the domain GPO level.

Note:

• Changing time settings against domain policy can cause authentication issues; coordinate with your admin.

7. CMOS/BIOS battery failing (clock resets)

Why this causes the problem:
If the motherboard battery is dead, the BIOS/UEFI clock resets when the PC is powered off, causing persistent wrong time until hardware is replaced.

Step-by-step solution:

1. Reboot and enter BIOS/UEFI (press Del, F2, or manufacturer key during boot).
2. Check the BIOS clock; if it’s wrong and resets after power loss, replace the CMOS battery (commonly CR2032).
3. After replacing battery, set correct BIOS time, boot Windows, then run w32tm /resync.

Tip:

• Symptoms: Time resets after unplugging power or full shutdown, or BIOS date is wrong.

8. Corrupted Windows Time configuration or permissions

Why this causes the problem:
If the Windows Time service registration or configuration is corrupted, it can’t perform NTP functions. Corruption may come from third-party apps, failed updates, or manual misconfiguration.

Step-by-step solution:

1. Open an elevated Command Prompt.
2. Stop and unregister the service:
   • net stop w32time
   • w32tm /unregister
3. Register and start the service again:
   • w32tm /register
   • net start w32time
4. Reset configuration to default NTP behavior:
   • w32tm /config /syncfromflags:DOMHIER /update (for domain) or use /syncfromflags:MANUAL /manualpeerlist:”time.windows.com” for standalone.
5. Run w32tm /resync /rediscover and check status with w32tm /query /status.

Note:

• If permissions are a problem, run a sfc /scannow and consider DISM repairs: DISM /Online /Cleanup-Image /RestoreHealth.

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Additional checks and diagnostic tools

• Event Viewer: Open Event Viewer → Applications and Services Logs → Microsoft → Windows → Time-Service → Operational. Look for Event IDs like 35, 36, 37, 47 for clues.
• Diagnostic commands:
  • w32tm /query /status — shows last sync and offset.
  • w32tm /query /peers — lists configured peers and states.
  • w32tm /stripchart /computer:time.windows.com /samples:5 /dataonly — measures offset to a server.
• Third‑party tools: NTP pool status pages (pool.ntp.org), or use Wireshark to confirm UDP 123 traffic.
• Virtual machines: If in VM, check host/guest time sync settings (VMware Tools, Hyper-V Integration Services) that may override Windows sync.

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FAQ

Q: Can I manually sync the clock any time?
A: Yes — run an elevated Command Prompt and use w32tm /resync; if that fails, add a manual NTP peer and rerun w32tm /resync /rediscover.

Q: How often does Windows sync time?
A: By default Windows polls the time source at intervals determined by the service (often every 7 days for clients); domain-joined machines follow domain DC cadence. You can change the polling interval via registry, but that’s advanced and not usually necessary.

Q: Will wrong system time cause other problems?
A: Yes — incorrect time can break authentication (Kerberos), TLS/SSL certificates, email, logging, scheduled tasks, and Windows Update.

Q: How do I change the NTP server to a custom one?
A: Use an elevated Command Prompt: w32tm /config /manualpeerlist:”your.ntp.server,0x9″ /syncfromflags:MANUAL /update then net stop w32time && net start w32time and w32tm /resync.

Q: My PC is on a company domain — should I sync to an Internet server?
A: Usually no. Domain controllers provide authoritative time; switching to an Internet server can break domain authentication. Consult your IT team.

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Conclusion

Most Internet time sync failures in Windows 10 come from a disabled or misconfigured Windows Time service, blocked NTP traffic, incorrect NTP server selection, or local settings like time zone and hardware clock. Follow the steps above to restart the service, set a reliable NTP server, open UDP 123, and verify with w32tm diagnostics to resolve cases where Internet time sync doesn’t work.