I have the same issue here at home as well as with 2 Windows PCs in the company.
I installed the crowdrender addon on both machines. On one machine, I am adding the other one as a new node. It is recognized and the right IP-address has been found. When I hit the connect button, there is a message in the blender top bar "connecting to nodes", which disappears after 3 seconds. Nothing else happens. The node stays grayed out without a status.
As I said, the exact same thing happens, when I try to connect 2 PCs in the company.
Also, signing into the Cloudrender cloud does not work. I enter my credentials and when I hit "login" nothing happens.
I am using the latest 2.79 (nightly) build with CR 0.16.
Any help would be much appreciated as I think that this is a fantastic tool...if it would only be working :-)