This is a guide intended to show some useful steps for troubleshooting Internet connectivity. Although not specific to ClearOS only, it can be useful if you cannot get out to the Internet.
Another guide exists for even greater detail that can be used generally for ALL types of network connections. If this does not help you with your issue, refer to that guide here.
You can work either forwards or backwards in this guide. I present them working your way backward since the conclusions seem to work better when presented this way. From the workstation which cannot get to the internet perform the following: