Fix Defender Definition Updates Falling Behind on a Metered Connection

Microsoft Defender on Windows 11 may stop downloading the latest virus and spyware definitions when your network is set as a metered connection. By default, Windows limits background data usage on metered networks to help you avoid exceeding your data cap. This article explains why Defender updates fall behind on metered connections and provides three reliable methods to force the updates through without permanently disabling the metered setting.

Why Microsoft Defender Definition Updates Stop on a Metered Connection

When you mark a Wi-Fi or Ethernet network as metered in Windows 11, the operating system treats it like a cellular data plan with a limited allowance. Windows Update, including the component that delivers Microsoft Defender definition updates, pauses automatic downloads to conserve bandwidth. This behavior is by design: Microsoft assumes you want to avoid large downloads that could push you over your data cap or incur overage charges.

Defender definition updates are relatively small, typically between 5 MB and 20 MB. However, Windows does not distinguish between a 500 MB feature update and a 10 MB security definition when enforcing metered network restrictions. The same policy that blocks Windows Update downloads also blocks Defender updates. As a result, your computer may show a warning in Windows Security that your virus and spyware definitions are out of date, leaving you vulnerable to new threats.

What Happens When Definitions Are Outdated

Outdated definitions mean Defender cannot detect recently discovered malware, ransomware, or zero-day exploits. The security app still runs and scans files, but it uses a stale signature database. If you connect to a public Wi-Fi network or open an email attachment while definitions are behind, the risk of infection increases significantly. Windows Security displays an amber or red warning on the Virus & threat protection tile when definitions are older than a few days.

Three Ways to Force Defender Definition Updates on a Metered Connection

You have three options to bring Defender definitions up to date. The first method is a one-time manual update. The second method changes a Windows Update setting to allow downloads over metered connections. The third method uses Group Policy or PowerShell for a permanent configuration on managed devices.

Method 1: Manually Check for Updates in Windows Security

This is the fastest way to update Defender definitions without changing any system settings. The manual update bypasses the metered network restriction for that single operation.

1. Open Windows Security
   Click the Start button, type Windows Security, and press Enter. Alternatively, right-click the shield icon in the system tray and select View security dashboard.
2. Go to Virus & threat protection
   In the left sidebar, click Virus & threat protection. On the main pane, look for the Virus & threat protection updates section.
3. Click Check for updates
   Under Security intelligence updates, click the Check for updates button. Windows Security will download and install the latest Defender definitions immediately, even if the network is metered. A progress bar appears, and the page displays the update version after completion.

This method works for a single update. If you disconnect and reconnect to the metered network, you must repeat these steps to stay current.

Method 2: Allow Download Updates Over Metered Connections in Windows Update

This setting tells Windows Update to download all updates, including Defender definitions, even on metered networks. It applies to the entire Windows Update pipeline, not just Defender.

1. Open Settings
   Press Windows key + I to open Settings. Click Windows Update in the left sidebar.
2. Access Advanced options
   On the Windows Update page, click Advanced options.
3. Open Delivery Optimization
   Scroll down to the Additional options section and click Delivery Optimization.
4. Enable downloads over metered connections
   On the Delivery Optimization page, click Advanced options. Toggle the switch under Download updates over metered connections to On. A confirmation dialog may appear — click Yes to confirm.

After enabling this setting, Windows Update will download Defender definitions automatically on metered networks. Note that this also allows other Windows updates, such as feature updates and driver updates, to download. If you have a strict data cap, monitor your usage after enabling this option.

Method 3: Configure Group Policy or PowerShell for Permanent Control

For IT-managed devices or advanced users, Group Policy or PowerShell can override the metered connection behavior specifically for Microsoft Defender updates without affecting other Windows Update downloads.

Using Group Policy Editor

1. Open Local Group Policy Editor
   Press Windows key + R, type gpedit.msc, and press Enter. This tool is available only on Windows 11 Pro, Enterprise, or Education editions.
2. Navigate to the Defender policy
   Go to Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus > Signature Updates.
3. Enable the policy for metered networks
   Double-click Allow definition updates on metered connections. Set it to Enabled. Click OK to save. This policy forces Defender to download definition updates regardless of the network metering status.

Using PowerShell

1. Open PowerShell as administrator
   Right-click the Start button and select Windows Terminal (Admin) or PowerShell (Admin).
2. Run the Set-MpPreference command
   Type the following command and press Enter:
   Set-MpPreference -MeteredConnectionUpdates $true
   This command tells Microsoft Defender to download definition updates on metered connections. No reboot is required.

The PowerShell method works on all editions of Windows 11, including Home. You can verify the setting by running Get-MpPreference | Select-Object MeteredConnectionUpdates.

Common Issues When Updating Defender on a Metered Connection

Manual Update Fails With Error 0x800705b4

Error 0x800705b4 indicates a timeout. This usually happens when the Defender update server is unreachable or the network is extremely slow. Wait a few minutes and try the manual update again. If the error persists, restart the Windows Security service by opening Services (services.msc), finding Windows Security Service, and clicking Restart.

Delivery Optimization Setting Does Not Appear

On some Windows 11 builds, the Delivery Optimization advanced settings may be hidden. If you do not see the toggle for Download updates over metered connections, use the PowerShell method instead. The Group Policy path also works on Pro editions.

Defender Definitions Still Show Outdated After Applying a Policy

Group Policy or PowerShell changes take effect immediately, but the current definition version does not update until the next scheduled check or a manual trigger. After applying the policy, open Windows Security and click Check for updates as described in Method 1 to force an immediate refresh.

Manual Update vs Delivery Optimization vs Group Policy: Comparison

Item	Manual Update (Method 1)	Delivery Optimization (Method 2)	Group Policy / PowerShell (Method 3)
Scope	Single Defender update only	All Windows Update downloads	Defender definition updates only
Persistence	One-time; resets after network reconnect	Permanent until toggled off	Permanent until policy or setting is reversed
Ease of use	Very easy; no settings changed	Easy; requires two Settings pages	Moderate; requires Group Policy or PowerShell
Edition support	All Windows 11 editions	All Windows 11 editions	PowerShell: all editions; Group Policy: Pro/Enterprise/Education only
Data usage impact	Minimal; only Defender definitions	Higher; all Windows updates allowed	Minimal; only Defender definitions

You now have three methods to keep Microsoft Defender definitions current on a metered connection. The manual update is best for occasional use. The Delivery Optimization setting works well if you trust that other Windows updates will not exceed your data cap. For precise control, use the PowerShell command Set-MpPreference -MeteredConnectionUpdates $true to allow only Defender updates without changing broader Windows Update behavior. After applying any method, verify the definitions are up to date by opening Windows Security and checking the Security intelligence version listed under Virus & threat protection updates.