Fix NS_E_WMP_SERVER_SECURITY_ERROR 0XC00D11E4

This error is a pain. Let's fix it.

You opened a stream or an online radio station in Windows Media Player, and boom — NS_E_WMP_SERVER_SECURITY_ERROR (0xC00D11E4). The player says it can't connect to the server. Don't toss your PC out the window. I've seen this dozens of times. Nine times out of ten it's a clock problem.

The quick fix — update your date and time

1. Click the clock in the bottom-right corner of your screen (system tray).
2. Click Date and time settings.
3. Turn Set time automatically to On (if it's not already).
4. Turn Set time zone automatically to On.
5. Click Sync now under Additional settings. You'll see a message that says "Syncing clock..." then "Your time is synced."
6. Close settings, reopen Windows Media Player, and try the stream again.

If it still fails, manually adjust:

1. Turn off Set time automatically.
2. Click Change under Set the date and time manually.
3. Set the correct date (month, day, year) and exact time. If you're unsure, check your phone or another device.
4. Click Change. The clock should update instantly.
5. Turn Set time automatically back on.
6. Try the stream again.

Why does the date and time cause this?

Windows Media Player uses SSL/TLS encryption to connect to secure streaming servers (https). Your PC checks the server's security certificate to make sure it's valid. The certificate has an issue date and an expiration date. If your computer's clock is off by more than a few minutes, the certificate looks expired or not yet valid. The player then refuses to connect. It's a security measure.

This happens more often than you'd think. Dead CMOS battery on an older PC, wrong time zone after travel, or a Windows update that messed up the clock. I've seen laptops that were in a drawer for a year come back with the date set to 2019.

If the clock fix didn't work — dig deeper

Try these in order. Skip the first one if you already did it.

Method 1: Reset Internet Explorer security settings (yes, even if you don't use IE)

Windows Media Player uses Internet Explorer's security settings under the hood.

1. Open the Control Panel. Type "Control Panel" in the search box next to Start.
2. Click Internet Options.
3. Go to the Advanced tab.
4. Click Reset under Reset Internet Explorer settings. A dialog box appears — check "Delete personal settings" if you want to clear history and saved passwords.
5. Click Reset. Wait for it to finish. You'll see a green checkmark.
6. Click Close, then OK.
7. Restart Windows Media Player and try the stream.

Method 2: Clear Windows Media Player cache

Corrupted cached data can cause timeouts and security errors.

1. Close Windows Media Player.
2. Press Windows Key + R. Type %userprofile%\Local Settings\Application Data\Microsoft\Media Player and hit Enter.
3. Delete everything in that folder. (Don't worry, WMP rebuilds it.)
4. Open Windows Media Player again. It might re-scan your media library. That's fine.
5. Test the stream.

Method 3: Disable TLS 1.0 / 1.1 (only if you're on Windows 10 22H2 or older)

Some older servers still use outdated TLS protocols. But newer Windows versions disable them by default.

1. Press Windows Key + R, type inetcpl.cpl, and hit Enter.
2. Go to the Advanced tab.
3. Scroll down to Security. Look for "Use TLS 1.0", "Use TLS 1.1", "Use TLS 1.2".
4. Make sure TLS 1.2 is checked. Leave TLS 1.0 and 1.1 unchecked (they're weak and can cause conflicts with newer security checks).
5. Click Apply, then OK.
6. Restart your browser and Windows Media Player.

Method 4: Check the firewall or antivirus

Some security software intercepts SSL connections and messes up certificate validation. Temporarily disable any third-party antivirus (like Norton, McAfee, or Avast) and see if the stream works. If it does, add Windows Media Player to the exception list in that software. Re-enable the antivirus after testing.

Less common scenarios that cause this error

• Corrupted user profile. Create a new local Windows user account and test WMP there. If it works, migrate your files to the new profile.
• Router date/time sync issue. Some routers act as NTP servers. If your router's clock is wrong, your PC might sync to it. Reboot the router, then sync your PC's clock again.
• The stream itself is dead. The server URL might have changed or the service shut down. Try a different, known-good stream (like a public radio station).
• IPv6 conflict. Disable IPv6 temporarily. Go to Control Panel > Network and Sharing Center > Change adapter settings. Right-click your connection, select Properties, uncheck Internet Protocol Version 6 (TCP/IPv6), click OK, then reboot.

How to prevent this from coming back

• Replace your CMOS battery if your clock resets every time you shut down the PC. It's a CR2032 coin cell — costs a few bucks and takes two minutes to swap.
• Keep Windows updated. Microsoft fixes time sync and SSL bugs in cumulative updates. Check for updates at Settings > Update & Security > Windows Update.
• Set a time sync schedule. Open Command Prompt as Administrator, run w32tm /resync to force sync. You can also run w32tm /config /update /manualpeerlist:time.windows.com to set a reliable NTP server.
• Don't install random media codec packs. Some of them replace system DLLs and break WMP's security checks. If you've got one, uninstall it and test again.

That should cover you. If none of these help, the stream's server might be using a self-signed or expired certificate that no amount of tweaking will fix. In that case, reach out to the stream provider and ask them to update their SSL certificate. Good luck.