KB: Cannot establish connection to private license server

Solution Details

Users may encounter the error:  "Cannot establish the connection to the license server"  This typically occurs when the port numbers used for client-server communication are blocked or not whitelisted. Follow the below steps to resolve the issue.

The default server port numbers for the license server are 9780 for HTTP and either 9785 or 443 for HTTPS. Please consult with your colleagues or server administrator to confirm which port number should be used for your license server connection

Troubleshooting Server Connectivity Issues

• Ping the Server for network connectivity check
• Test Browser interface access
• Verify Port connectivity using Telnet Command
• Check Firewall Rules

Ping the Server for network connectivity check

1. Press the Windows key + R to open the Run dialog box.
2. Type cmd and press Enter or click OK.
3. Ping the server  and check the reply for example "Ping<space> <Server IP address>".
4. A successful reply indicates no Network connectivity issue.
     If you see "Request timed out" reply then the server is unreachable or A VPN connection is required but not enabled. 

In Altium Designer, this may also appear as: "The request has timed out." Refer below screenshot

Test Browser interface access

1. Open a web browser on the client PC.
2. Enter the server address with port number, e.g. http://<ServerName>:9780 or https://<ServerName>:9785
3. Check whether you are able to access the server through browser.
     If you see "The site cannot be reached" error message then there may be a connectivity or firewall issue 

Verify Port connectivity using Telnet Command

Make sure that the "Telnet Client" windows feature is enabled on your PC. To do this, Go to Control Panel ->Navigate to Programs and Feaures -> Choose "Turn windows featres on or off -> Enable the "Telnet Client" ->Click Ok to apply the changes

• Install Telnet Client
• Telnet syntax and example

Once the Telnet Client is successfully installed, follow the steps below to verify the server connection using the specified port number

1. Press the Windows key + R to open the Run dialog box.
2. Type cmd and press Enter or click OK.
3. Run Telnet command and Ping the server with port number
4. For example "Telnet servername 9780"

telnet [domain name or ip address] [port]

5. If the connection is successful, a blank screen will appear. If the connection fails, you will see an error message such as: "Could not open connection to the host, on port 9780: Connection failed"

Check Firewall Rules 

To ensure the license server ports are not being blocked by the firewall. Check the Inbound and outbound rules on your Client PC. 

1. Open Windows Firewall with Advanced Security
2. Go to Inbound Rules
3. Ensure ports 9780, 9785, or 443 (used by Altium Designer) are not blocked.
4. Consult your IT or Network Admin to:
     • Confirm these ports are open on the firewall, VPN, or any security software.

• Windows Inbound and Outbound rule reference

Additional Troubleshooting references 

• Troubleshoot License access
• KB: Cannot connect to Altium Infrastructure Server (AIS) to use private license