hi Patrick,
To start with please check the following.
Make sure your CueCore and your computer are within the same IP range. For example:
CueCore: IP=192.168.1.10 subnet=255.255.255.0
Computer: IP=192.168.1.9 subnet= 255.255.255.0
Check that sure your computer has only one network adapter enabled. If you connect via wire-interface, then make sure wifi-interfaces are disabled.
Make sure your CueCore is running firmware 1.50 or higher. You can upgrade your firmware inside CueluxPro using the 'network' menu.