Issue to RDP

Question

Issue to RDP

Peter_1985 3,151

Hi,

Only today, I could not use RDP to get into the server but at the same time, it is fine to VNC to get into that. What can be the issue? How to identify the exact reasons?

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Answer 1

Harry Phan 15,915 Independent Advisor

Hello Peter,

If RDP stopped working while VNC still connects, the issue is isolated to Remote Desktop Services. First check if the TermService is running with sc query termservice; restart it if needed. Verify port 3389 is listening using netstat -ano | findstr 3389. If not, the RDP listener may be disabled—inspect HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp and ensure it’s active.

Confirm firewall rules allow inbound 3389 by checking “Remote Desktop (TCP-In)” in wf.msc. Review Event Viewer under TerminalServices-RemoteConnectionManager and LocalSessionManager for errors. Also check that “Allow remote connections” is enabled in System Properties or via GPO under Remote Desktop Session Host > Connections.

By validating service status, port listener, firewall, and event logs, you can pinpoint whether the failure is due to service corruption, blocked traffic, or policy misconfiguration.

I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!

Harry.

Peter_1985 3,151 Reputation points

2026-01-04T13:13:07.9933333+00:00

I checked termservice is running. And it is listening on 3389 and Firewall is also allowing the port 3389 below.

There was no other change to the server. Why did the issue happen?
Peter_1985 3,151 Reputation points

2026-01-06T03:30:44.2966667+00:00

Any help?
Peter_1985 3,151 Reputation points

2026-01-07T06:37:22.57+00:00

Any help? Can you urgently help?
Peter_1985 3,151 Reputation points

2026-01-08T09:14:31.2633333+00:00
I ping that IP (for this) and got. What is the reason?

C:\Windows\system32>ping 1?.?.?.?

Pinging 1?.?.?.? with 32 bytes of data:

Request timed out.

Request timed out.

Request timed out.

Request timed out.

Ping statistics for 1?.?.?.?:

Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
Harry Phan 15,915 Reputation points Independent Advisor

2026-01-08T12:22:47.45+00:00

Since TermService is running, port 3389 is listening, and the firewall allows RDP, the service itself is healthy. The fact that VNC connects but RDP fails points to a network or authentication issue rather than a local service failure. Ping timeouts show ICMP is blocked, which is common, but they also suggest possible upstream filtering. If RDP traffic is being dropped, it is likely due to a firewall, VPN, or IDS/IPS rule change outside the server. Another possibility is that Network Level Authentication is enabled, and the connecting client cannot negotiate NLA, causing RDP to fail while VNC still works. Event Viewer under TerminalServices-RemoteConnectionManager will confirm if authentication errors are occurring. Testing RDP from a client on the same subnet as the server helps isolate whether the problem is network path filtering or local configuration. If local connections succeed but remote ones fail, the issue is external filtering. If all connections fail, review NLA and TLS settings on the server.
Harry Phan 15,915 Reputation points Independent Advisor

2026-01-08T12:23:22.1266667+00:00

Let me know.
Peter_1985 3,151 Reputation points

2026-01-09T01:33:28.4333333+00:00

Thanks a lot.

Answer 2

If you are able to connect to the server using VNC but not through RDP, there could be several reasons for this issue. Here are some potential causes and steps to identify the exact reasons:

Remote Access Not Enabled: Ensure that remote access is enabled on the server. If it's not enabled, you won't be able to connect via RDP.
RDP Listener Issues: The RDP-TCP listener may not be functioning correctly. You can check if the listener is active and properly configured.
Firewall Configuration: Check the firewall settings to ensure that RDP traffic (TCP port 3389) is allowed. You can verify this by checking the inbound rules in the Windows Firewall settings or using PowerShell commands to ensure that the Remote Desktop rules are enabled.
Network Configuration: Verify that the server is reachable on the network. If there are any network issues or restrictions, they could prevent RDP connections.
Anti-Virus Interference: Sometimes, anti-virus software can block RDP connections. If possible, try temporarily disabling the anti-virus to see if it resolves the issue.
User Permissions: Ensure that the user account you are using has the necessary permissions to access the server via RDP. If the account is not authorized for remote login, you will encounter access denied errors.

To troubleshoot, start by checking the RDP settings and firewall rules, and then verify the network connectivity to the server. If the issue persists, you may need to consult with Microsoft Support for further assistance.

References:

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Issue to RDP

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