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Updated on in How to, Troubleshooting

VNC Viewer Not Connecting – Errors, Fixes and Solutions.

Author: Helga York
Helga York Article author

The development of Virtual Network Computing (VNC) has revolutionized today’s remote workforce. Among VNC software nowadays, RealVNC stands out as one of the biggest names. It’s a tool that provides secure and reliable remote access across Windows, MacOS, or Linux machines.

However, many RealVNC users encounter connection issues when trying to start a session using the software’s VNC Viewer. In particular, a prompt like “VNC Viewer Not Connecting” may appear. Oftentimes, this problem is due to network restrictions, misconfigurations, or faulty firewall settings.

In this article, we’ll help you overcome this problem and other common RealVNC connection issues. We provide thorough guides to troubleshoot VNC connection issues and properly configure network, firewall, and VNC server settings. 

Let’s get started!

Useful tip: 
The best way to cope with common VNC problems is to switch to an alternative solution. We recommend HelpWire, a reliable and efficient remote desktop tool, catered towards independent professionals and small to medium-sized businesses offering a modern and streamlined interface that is easy to navigate with optimized features for remote support. Try HelpWire today for a hassle-free solution to your VNC Viewer issues.

Common RealVNC Connection Errors & How to Fix Them

VNC connection failures with RealVNC are typically caused by network issues, incorrect settings, or firewall restrictions. It can be tricky diagnosing the root cause, but the specific error message can point you in the right direction.

Here are some common RealVNC connection errors, together with their “indicative” error message and potential causes. You’ll also see our suggested steps to fix them.

1. Connection Refused by the Computer

Error Message:

“The connection was refused by the computer”

This error happens when the server refuses to accept inbound connections because of misconfigurations or restrictions.

Possible Causes:

      • • The VNC Server is not running or misconfigured.
      • • Firewall or antivirus is blocking the connection.
      • • Incorrect IP address or port is being used.
      • • The VNC Server is not listening for incoming connections.

Solutions:

  1. Ensure the VNC Server is running on the remote machine.
  2. Restart both VNC Server and Viewer.
  3. Check firewall settings and allow VNC ports (5900, 5800).
  4. Verify that the correct IP address and port are used in the VNC Viewer.
  5. Make sure VNC Server is configured to accept connections.

2. Connection Timed Out (10060)

Error Message:

“Connection: Connection timed out (10060)”

A timeout error means that VNC Viewer was unable to establish a connection within the expected timeframe. This usually happens when the server is unreachable due to network issues or blocked ports.

Possible Causes:

    • • The VNC Server is unreachable over the network.
    • • Firewall or security software blocks the connection.
    • • The VNC port is not open or incorrectly configured.

Solutions:

  1. Check network connectivity using ping or nmap.
  2. Verify that VNC Server is running and listening on the correct port.
  3. Allow VNC traffic through firewall (iptables on Linux, Windows Firewall rules).
  4. Ensure that the remote machine is awake and connected to the network.
  5. If connecting over the internet, configure port forwarding on the router.

3. VNC Server is Not Currently Listening for Cloud Connections

Error Message:

“VNC Server is not currently listening for cloud connections”

This error indicates that RealVNC’s cloud connectivity is disabled or unavailable, preventing the client from connecting through the cloud relay service.

Possible Causes:

  • • Cloud-based access is disabled on the VNC Server.
  • • Network restrictions prevent cloud access.
  • • The RealVNC service is down.

Solutions:

  1. Open VNC Server settings and enable cloud connectivity.
  2. Check internet access on the remote machine.
  3. Restart the VNC Server to refresh its status.
  4. Verify that your RealVNC subscription allows cloud access.

4. Unable to Connect to VNC Server Using Your Chosen Security Setting

Error Message:

“The connection could not be established due to security setting mismatches.”

VNC Viewer cannot connect because the security configurations on the server and viewer do not match. Encryption or authentication settings may be incompatible.

Possible Causes:

  • • Mismatch between VNC Viewer and Server encryption settings.
  • • Outdated VNC software versions.

Solutions:

  1. Update both VNC Viewer and VNC Server to the latest versions.
  2. Adjust security settings in the VNC Server to match the viewer.
  3. If using encryption, ensure that the viewer supports the selected security type.

5. Firewall Blocking VNC Connection

Error Message:

No specific error, but VNC does not connect.

If a firewall is blocking VNC, the connection request is intercepted before reaching the server, preventing successful communication between the client and host.

Possible Causes:

  • • Windows Defender Firewall or Linux iptables is blocking VNC traffic.
  • • The required VNC ports (5900, 5800) are not open.


Solutions:

On Windows:

  1. Open Windows Defender Firewall → Allow an app → Add vncserver.exe and vncviewer.exe.
  2. Open Command Prompt and run:

netsh advfirewall firewall add rule name="VNC" dir=in action=allow protocol=TCP localport=5900

On Linux:

  1. Open a terminal and run:

sudo ufw allow 5900/tcp

sudo systemctl restart firewalld

2. For iptables:

sudo iptables -A INPUT -p tcp --dport 5900 -j ACCEPT

For both cases restart VNC Server after firewall changes.

6. Port Conflict Issue

Error Message:

“VNC Server is already running on this port.”

A port conflict occurs when another service is already using the port assigned to VNC, leading to failed connection attempts or unexpected behavior.

Possible Causes:

  • • Another service is using the same port as VNC.
  • • Multiple VNC instances are running on the same port.

Solutions:

  1. Change the VNC port to an unused one (e.g., 5901).
  2. Restart the VNC service and check port usage:
    netstat -tulnp | grep 5900
  3. If another application is using the port, reconfigure the VNC Server.

7. VNC Not Listening on Correct Port

Error Message:

No response from the VNC Server.

When the VNC Server is configured to use a non-standard port, the client may fail to connect if the correct port is not specified or accessible.

Possible Causes:

  • • The VNC Server is configured to use a non-default port.
  • • The Viewer is attempting to connect on the wrong port.

Solutions:

  1. Open VNC Server settings and check the configured port.
  2. Ensure the correct port is used in VNC Viewer (e.g., 192.168.1.10::5901).
  3. Restart the VNC service to apply changes.

 

Final Troubleshooting Steps 

• Restart the router and network devices to ensure connectivity.
• Reinstall the VNC Server and Viewer to reset configurations.
• Check the updates for VNC Software
• Check RealVNC’s status page for any service outages.

If you have gone through all the above steps but you are still experiencing a problem, then log a support ticket with RealVNC here.

Switch to a Reliable Alternative to VNC Viewer

If you’re encountering difficulties with VNC Viewer, consider HelpWire, a free remote desktop software for Windows, Linux and macOS. This free alternative to VNC Viewer provides essential tools for efficient customer support on both Mac and PC, accessible from anywhere. Notably, HelpWire is freely available for both personal and business use. It features a user-friendly interface, which allows for easy and quick setup of remote support sessions, reducing the complexity typically associated with such configurations.

Key Features of HelpWire:

  • Cross-Platform Remote Support:

    HelpWire facilitates smooth assistance for users on both Windows and macOS, offering compatibility and ease of use across various operating systems.

  • Unattended Remote Access:

    Unattended Remote Access is a HelpWire leading-edge feature offering customers flawless access to remote workstations even without the need for the end user’s presence. Gain real-time control of devices, enjoy uninterrupted access, switch users seamlessly, and restart connection anytime, anywhere.

  • Efficient Support Session Initiation:

    Teams can swiftly start support sessions using a unique HelpWire client application link, making the connection process more straightforward.

  • Hassle-Free File Sharing:

    Easily transfer files to and from remote client devices, improving the support experience.

  • Advanced Client Management:

    The operator account in HelpWire includes comprehensive features for client management, aimed at increasing user satisfaction.

FAQ

For users of macOS Mojave (10.14) upwards, you must give explicit permission to VNC Connect for Screen Recording and Accessibility. Without it, you will see a blank screen, or only have view access when using VNC Viewer.

To allow screen recording, go to System Preferences > Security & Privacy > Privacy > Screen Recording.
Accessibility options can be amended here: System Preferences > Security & Privacy > Privacy > Accessibility.

VNC only works when there is a monitor physically connected. If you connect to a headless computer (a computer with no monitor attached) or if the server’s HDMI/Display port is connected but powered off – you will be faced with a black screen when you try to connect to the server. The VNC Server uses DirectX to capture graphical updates, but without a monitor, Windows is unable to report any updates and therefore you will only see a black screen.

Some steps to resolve this problem:

  1. Version 6.5.0 of VNC Server includes an upgrade to recover from a blank screen, upgrade to at least this version.
  2. Adjust your power settings on the server to never turn off the display.
  3. Disable any Battery Saver modes on the server.
  4. Use an EDID emulator.
  5. Make the following changes on the VNC Server CaptureMethod parameter.
    • ◦ Open the VNC Server on the server machine.
    • ◦ Click on the menu and select Options.
    • ◦ Locate CaptureMethod in the Expert tab and change the value to 1.
    • ◦ Restart the VNC Server.

To Copy and Paste during a VNC session works the same as usual. Windows users can use the Ctrl+C, Ctrl+V combination. Mac Users use Cmd+C and Cmd+V. If however your server is a Mac and you’re connecting from a Windows machine, you need to press Alt+C instead of Cmd+C.

Copy and Paste only works with text. You cannot copy images, drag-and-drop files or other non-text items.

Should you experience any problems consider the following:

  1. If you have copied a large amount of data that exceeds 256kb, you will not be able to paste it. Instead the most recent item in the Clipboard will be pasted.
  2. It is possible that the copy/paste feature has been disabled on your VNC Server. You can check by accessing the global permissions from the VNC Server Options > Users & Permissions menu.
  3. The ability to copy and paste may be user specific. Check if you have permissions in the VNC Server Options > Users & Permissions settings screen.

If you can’t see the mouse during a VNC session, or you can only see a dot, then the most likely explanation is that there is no mouse connected to the VNC Server. The easiest way, if you have access, is to attach a mouse to the server. If you can’t do this, then try changing the VNC Server settings as follows:

Windows 10 Users:
Enable the “Use numeric keypad to move mouse around the screen” option from Start > Settings > Ease of Access > Mouse.

Windows 7 Users:
Open the Control Panel and select Mouse. From the “Pointer Options” tab, toggle the “Display pointer trails” option on or off. Click Apply to save your changes.

Tags:
Tips & Tricks, VNC