RDP ClientActiveX Has Been Disconnected Reason 4

If you see the error “RDP ClientActiveX has been disconnected (Reason Code: 4)”, it usually means the Remote Desktop session was unexpectedly terminated because of a network interruption, Remote Desktop Services issue, server configuration problem, or session timeout. In most cases, the problem can be fixed by checking your internet connection, Remote Desktop settings, firewall rules, Windows updates, and server resources.

This guide explains what RDP ClientActiveX Has Been Disconnected Reason 4 means, why it happens, and how to fix it permanently.

What Does “RDP ClientActiveX Has Been Disconnected Reason 4” Mean?

The Microsoft Remote Desktop client (mstsc.exe) uses an ActiveX component to establish and maintain Remote Desktop Protocol (RDP) sessions.

When Windows displays:

ClientActiveX has been disconnected. Reason 4

it indicates that the RDP connection ended unexpectedly before the session could continue normally.

Unlike authentication errors, Reason 4 usually points to communication problems between the client and the Remote Desktop server.

Common Causes of RDP ClientActiveX Reason 4

Several issues can trigger this error.

1. Unstable Internet Connection

Network interruptions are the most common cause.

Examples include:

• Wi-Fi signal drops
• ISP interruptions
• High latency
• Packet loss
• VPN instability

Even a brief network interruption can disconnect an RDP session.

2. Firewall Blocking RDP Traffic

If TCP port 3389 becomes blocked by:

• Windows Firewall
• Antivirus
• Corporate firewall
• Router

the session may disconnect unexpectedly.

3. Remote Desktop Session Timeout

Many Windows Servers automatically disconnect inactive users after a predefined time.

Common timeout policies include:

• Idle timeout
• Active session limit
• Disconnected session timeout

4. Windows Updates

After installing Windows updates:

• RDP services restart
• Network drivers reload
• Remote Desktop Services restart

This temporarily disconnects connected users.

5. High Server Resource Usage

If the server experiences:

• 100% CPU
• Low RAM
• Disk bottlenecks

Remote Desktop Services may stop responding.

6. Network Driver Problems

Outdated or corrupted NIC drivers can interrupt RDP traffic.

7. Remote Desktop Service Restart

If the service:

Remote Desktop Services (TermService)

restarts automatically, all active sessions disconnect immediately.

8. VPN Problems

VPN software may:

• Change routes
• Drop packets
• Switch gateways
• Disconnect temporarily

All of these can trigger Reason 4.

Symptoms

Users commonly notice:

• RDP window suddenly closes
• Black screen before disconnecting
• “Attempting to reconnect…”
• ClientActiveX error message
• Random disconnects every few minutes

How to Fix RDP ClientActiveX Has Been Disconnected Reason 4

Solution 1: Test Your Internet Connection

Run:

ping google.com -t

or

ping <Your Server IP> -t

Look for:

• Packet loss
• High latency
• Request timed out

If problems appear, fix the network before troubleshooting Windows.

Solution 2: Restart Remote Desktop

Close Remote Desktop completely.

Then reconnect.

Sometimes the ActiveX component simply needs a fresh session.

Solution 3: Restart the Server

If you manage the server:

Restart Windows.

Many temporary RDP issues disappear after a reboot.

Solution 4: Check Firewall Rules

Verify that TCP port 3389 is allowed.

Check:

• Windows Defender Firewall
• Router
• VPS firewall
• Cloud firewall
• Antivirus firewall

Solution 5: Disable Session Timeouts

Open:

gpedit.msc

Navigate to:

Computer Configuration

Administrative Templates

Windows Components

Remote Desktop Services

Remote Desktop Session Host

Session Time Limits

Set:

• No session timeout
• No idle timeout

Restart the server.

Solution 6: Update Windows

Install the latest:

• Security updates
• Cumulative updates
• RDP patches

Microsoft regularly fixes Remote Desktop bugs.

Solution 7: Update Network Drivers

Open Device Manager.

Expand:

Network adapters

Update:

• Ethernet driver
• Wi-Fi driver
• Virtual NIC
• Hyper-V adapter

Solution 8: Disable UDP Temporarily

Some unstable networks perform better using TCP only.

Open:

gpedit.msc

Go to:

Remote Desktop Services

Remote Desktop Connection Client

Enable:

Turn Off UDP On Client

Restart the computer.

Solution 9: Check Event Viewer

Open:

eventvwr.msc

Review:

Applications and Services Logs

Microsoft

Windows

TerminalServices

Look for:

• Error
• Warning
• Network interruption
• Licensing errors

These logs often reveal the exact cause.

Solution 10: Monitor Server Resources

Open Task Manager.

Check:

• CPU usage
• RAM usage
• Disk activity
• Network activity

If resources remain above 90%, upgrade the server or reduce workload.

Quick Troubleshooting Checklist

Prevent Future Disconnects

To minimize future Reason 4 errors:

• Use a wired internet connection.
• Keep Windows fully updated.
• Avoid overloaded servers.
• Monitor CPU and memory usage.
• Use enterprise-grade hosting.
• Configure Remote Desktop timeouts correctly.
• Update network drivers regularly.
• Maintain stable VPN configurations.
• Use uninterrupted power for servers.

Conclusion

The RDP ClientActiveX Has Been Disconnected Reason 4 error is generally caused by network instability, firewall restrictions, Remote Desktop timeout policies, outdated drivers, or server resource limitations. By systematically checking connectivity, updating Windows and drivers, reviewing firewall settings, monitoring server performance, and adjusting Remote Desktop session policies, you can eliminate most occurrences of this error. Keeping your server properly maintained and your network stable will ensure more reliable and uninterrupted Remote Desktop connections.