Problems connecting with our server can depend on different things. 

In some rare cases, our server becomes temporarily overloaded. Then just wait for a couple of minutes and try again.

You could have a firewall installed that only let traffic through to sites previously approved by a network technician. There could be that all your traffic is going through a proxy server and that you will have to configure the settings for the proxy server in CNC Simulator (you will get a chance to do that if the startup fails). It can also happen if you have an unreliable connection to the Internet, as a weak Wi-Fi signal for example. In any case, if you can’t solve the problem yourself, you will need to contact your ISP (Internet Service Provider) or if you are at an institution or a company, the network technician or the person in charge of the internal network.

Make sure that there is a rule or an exception in the firewall software that allows traffic from the cncsimulator.exe file to the server over port 80. This is very important and one of the most common sources of failure. Without this permission, CNC Simulator Pro can not start as it needs to "phone home" to check the license.