GlobalProtect Blocking Your CAC? The VPN Fix for DoD Networks

GlobalProtect VPN is essential for remote access to DoD networks, but it’s also one of the most frustrating applications to get working with a CAC. Connection failures, certificate errors, and authentication timeouts are common—and the error messages are rarely helpful. Here’s how to diagnose and fix GlobalProtect CAC issues.

How GlobalProtect Uses Your CAC

When you connect to a DoD network via GlobalProtect, the VPN client:

1. Contacts the VPN gateway and initiates a secure connection
2. Requests your authentication certificate from your CAC
3. Prompts for your PIN to unlock the certificate
4. Presents the certificate to the gateway for verification
5. Establishes the encrypted tunnel if everything checks out

This process can fail at any step, and the symptoms often look the same: “Connection failed” or “Authentication error.”

Before You Troubleshoot

Verify these basics first:

• CAC is valid: Check the expiration date on your card
• Reader is connected: LED should be lit, card fully inserted
• Windows sees your CAC: Open Certificate Manager (certmgr.msc) and check Personal certificates
• Middleware is running: ActivClient or your CAC middleware should be active in the system tray
• Internet connection works: Can you reach regular websites?

If any of these aren’t working, fix them first. GlobalProtect can’t authenticate if your CAC isn’t functioning properly at the system level.

Common Issue #1: Certificate Not Found

You click Connect, and GlobalProtect either shows no certificates or says it can’t find a valid certificate.

Causes

• CAC not fully inserted or reader not recognized
• ActivClient/middleware not running
• DoD root certificates not installed
• Certificate chain is broken

Solutions

Step 1: Reconnect your CAC reader

1. Remove the CAC from the reader
2. Unplug the reader from USB
3. Wait 10 seconds
4. Plug the reader back in
5. Wait for Windows to recognize it (you’ll hear the USB sound)
6. Insert your CAC

Step 2: Restart the Smart Card service

1. Press Windows + R, type services.msc, press Enter
2. Find “Smart Card” in the list
3. Right-click and select “Restart”
4. Also restart “Smart Card Device Enumeration Service” if present

Step 3: Install/update DoD certificates

1. Download InstallRoot from MilitaryCAC.com
2. Run it as Administrator
3. Click “Install Certificates”
4. Restart your computer

Common Issue #2: PIN Prompt Never Appears

GlobalProtect seems to be trying to connect, but you never get a PIN prompt. The connection eventually times out.

Causes

• PIN dialog is appearing behind other windows
• ActivClient isn’t intercepting the PIN request
• Windows Credential Manager is cached incorrectly

Solutions

Check for hidden windows:

1. Press Alt+Tab to cycle through open windows
2. Look for the ActivClient or Windows Security PIN prompt
3. The dialog may have appeared on a secondary monitor

Clear cached credentials:

1. Open Control Panel → Credential Manager
2. Look for any entries related to your VPN gateway
3. Remove them
4. Try connecting again

Restart ActivClient:

1. Right-click the ActivClient icon in the system tray
2. Select Exit
3. Open ActivClient from the Start menu
4. Try GlobalProtect again

Common Issue #3: Connection Drops During Authentication

You enter your PIN, but the connection fails immediately after or during the authentication process.

Causes

• CAC reader losing power or connection
• USB hub instability
• Network interruption during handshake
• Firewall blocking the connection

Solutions

Use a direct USB connection:

• Connect the reader directly to your laptop, not through a hub or dock
• Use a rear USB port on desktops (more stable power)
• Avoid USB extension cables during VPN connection

Disable power saving for USB:

1. Open Device Manager
2. Expand “Universal Serial Bus controllers”
3. Right-click each USB Root Hub → Properties
4. Under “Power Management,” uncheck “Allow the computer to turn off this device to save power”

Check your firewall:

• Temporarily disable third-party antivirus/firewall
• Try connecting
• If it works, add GlobalProtect to your firewall’s exception list

Common Issue #4: “Authentication Failed” After Entering PIN

You enter your PIN correctly, but GlobalProtect says authentication failed.

Causes

• Expired CAC certificate
• System date/time is incorrect
• Wrong certificate being selected
• VPN gateway configuration issue (not on your end)

Solutions

Check your system time:

1. Right-click the clock in the taskbar
2. Select “Adjust date/time”
3. Enable “Set time automatically”
4. Click “Sync now”

Certificate validation fails if your computer’s time is significantly off from the server’s time.

Check certificate expiration:

1. Press Windows + R, type certmgr.msc, press Enter
2. Expand “Personal” → “Certificates”
3. Find your DoD certificates and check expiration dates
4. If expired, you need a new CAC

Manually select the correct certificate:

If GlobalProtect is selecting the wrong certificate:

1. When the certificate selection dialog appears, look carefully at the options
2. Select the certificate labeled “DOD ID CA” for authentication (not EMAIL)
3. Check “Remember this decision” if the option appears

Common Issue #5: “Portal Cannot Be Reached”

GlobalProtect can’t even connect to the VPN portal before authentication begins.

Causes

• Network connectivity issues
• DNS resolution problems
• VPN gateway is down
• Local network is blocking VPN ports

Solutions

Test basic connectivity:

1. Open Command Prompt
2. Ping the VPN gateway: ping vpn.your-base.mil
3. If ping fails, try: nslookup vpn.your-base.mil

Try a different network:

• Some home routers or public WiFi block VPN ports
• Try using your phone as a mobile hotspot
• If that works, your home network is the problem

Flush DNS cache:

1. Open Command Prompt as Administrator
2. Run: ipconfig /flushdns
3. Try connecting again

GlobalProtect-Specific Settings

Some issues are specific to GlobalProtect configuration:

Check GlobalProtect Version

Older versions may have CAC compatibility issues. Check if an update is available:

1. Right-click the GlobalProtect icon in the system tray
2. Select “Settings” or “About”
3. Compare your version to what your IT department recommends

Clear GlobalProtect Cache

1. Close GlobalProtect completely
2. Navigate to C:Users[username]AppDataLocalPalo Alto Networks
3. Delete the GlobalProtect folder
4. Restart GlobalProtect

This forces GlobalProtect to rebuild its configuration and certificate cache.

When It’s Not Your Problem

Sometimes the issue is server-side:

• Gateway maintenance: VPN servers have scheduled downtime
• Capacity limits: During high-demand periods (Monday mornings, exercises), servers may reject connections
• Certificate revocation list issues: The server can’t check if your certificate is valid
• Configuration changes: Your IT department may have changed gateway settings

If multiple people are having the same issue at the same time, it’s probably not your local configuration. Contact your help desk.

Best Practices for Reliable VPN Connection

• Insert CAC before launching GlobalProtect: Let Windows fully recognize the card first
• Use a dedicated USB port: Always use the same port for your reader
• Connect before opening email/apps: Establish VPN before launching Outlook or other DoD applications
• Keep middleware updated: Install ActivClient updates when available
• Maintain DoD certificates: Run InstallRoot periodically to ensure root certificates are current

Quick Troubleshooting Checklist

1. [ ] CAC inserted and reader LED is lit
2. [ ] Can access CAC certificates in certmgr.msc
3. [ ] System time is accurate
4. [ ] ActivClient is running
5. [ ] DoD root certificates are installed
6. [ ] Using direct USB connection (not through hub)
7. [ ] Can ping VPN gateway
8. [ ] Firewall isn’t blocking GlobalProtect
9. [ ] No other VPN clients are running

Work through this list before contacting your help desk. Most GlobalProtect CAC issues come down to one of these items.

Getting Help

If you’ve tried everything and still can’t connect:

1. Document the error: Screenshot the exact error message
2. Note what you’ve tried: IT support will ask what troubleshooting you’ve done
3. Contact your local help desk: They can check if there are known issues with the gateway
4. Try from a different location: If possible, test from another network to rule out local network issues

VPN issues are common enough that your IT department has probably seen your specific problem before.

Last updated: December 2025. GlobalProtect versions and configurations may vary by organization.

About John Bigley

John Bigley is a former DoD IT specialist with over 12 years of experience supporting CAC authentication systems and military network infrastructure. He specializes in troubleshooting smart card issues and helping service members navigate DoD technology requirements.