SolidWorks Client cannot connect to License Server

SolidWorks Client cannot connect to License Server

One of the most common issues we see with SolidWorks network licenses is that the SolidWorks Client cannot communicate with the license server. When this happens, you will get a license error when opening SolidWorks on a client machine.

There are 2 common reasons for this:

1 - The server is unreachable - commonly due to a networking issue.
2 - There is a firewall running on the server that is keeping the client from communicating on port 25734

To test both of these, there are two simple procedures:

1 - First, ping the server from the client computer. Ping the server by both its IP address and its computer name. If you do not get a response or if you only get a response on IP or computer name, you'll first need to investigate this. After you can ping the server from the client, try launching SolidWorks. 

2 - If SolidWorks still returns a license server communication error, move on to running a Telnet test. Please note, Telnet is not enabled by default in some Windows operating system. To determine how to enable it, search the internet for "Enabling Telnet on xxx" where xxx is your systems operating system version. 

      Telnet Test:

      1. To telnet into the server port open a command prompt on the client (Start > Run > type cmd and hit enter)

      2. Type "telnet server_name port_number" (without the quotation marks) and hit enter.  The default inbound port number is 25734

      3. If the screen comes back with a blinking cursor the telnet succeeded

      4. If the telnet failed try substituting the server_name with the IP address of the server.

      5. If the telnet still fails there is a TCP/IP problem between the client and the server and it should be investigated by the network administrator. It is possible that a firewall could be blocking communication on that specific port (25734).


If Telnet fails, it is likely a firewall issue.
To create Firewall exception rules for SOLIDWORKS® SolidNetWork License Manager (SNL), follow these steps:

• Note that these steps may vary depending on the Windows Server® version.

1. From the Windows Server machine, go to ‘Start’ > ‘Control Panel’ > ‘Security and System’ > ‘Windows Firewall’.
2. In the left pane, click the ‘Advance settings’ link.
3. Select the ‘Inbound Rules’ and right-click to choose ‘New Rule’.
4. Select ‘Port’ and then click ‘Next’.
5. Make sure ‘TCP’ is selected > for ‘Specific local port’ type ‘25734’ > click ‘Next’.
6. Select ‘Allow the connection’ (which should be the default selection) and then click ‘Next’.
7. Select the desired Profile to apply the exception (select all the profiles if unsure).
8. Type a name for the rule and then click ‘Finish’.
9. Repeat steps 3 through 8 for port ‘25735’.
10. On the server, run the SOLIDWORKS SolidNetwork License Manager program.
11. In the SNL Manager, select the option to modify the installation and then click ‘Next’. 
12. Make sure that option ‘A firewall is in use on this server’ is active and that the ports you configured  are selected to be opened in the firewall.
13. Proceed through the wizard. If the settings have been changed, stop and then restart the server to apply the new settings.


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