If your build server is using a self-signed certificate, CatLight may not be able to connect and will show a message like "SSL connect error". This happens because the SSL certificate of your server is not trusted by your operating system. 

Add this certificate as trusted to resolve the problem, and try connecting again.

Instructions for Windows:
https://blogs.technet.microsoft.com/sbs/2008/05/08/installing-a-self-signed-certificate-as-a-trusted-root-ca-in-windows-vista/ 

For OS X:
http://www.robpeck.com/2010/10/google-chrome-mac-os-x-and-self-signed-ssl-certificates 

For Linux:
http://askubuntu.com/questions/530056/install-root-certificate-on-ubuntu-14-04-64-bit