This issue can be caused by many things. The following is a step by step guide to troubleshoot this problem:

1. Make sure you are not the only one having problems connecting.

* If you are the only one having a problem connecting to your server, you may have a firewall issue on your router.

* Your computer may also have a firewall rule blocking MX Simulator from accessing the server.

2. Make sure the server is on.

* This may seem obvious but it is worth double checking. Stop and start the server just to be sure.

3. Check the server log in the settings page to see if it is giving any errors.

* This may directly tell you what the issue is or at the very least it will help us narrow down the possible issues.

4. Double check your settings page and verify each setting is in the proper format.

* This is the most common cause of issues with servers not turning on properly. Follow the examples next to the text fields for each setting to verify they are in the expected format.

5. If all the above steps fail to fix your issue, create a support ticket.