NRC has received some updates for the 2019.1 release. Node Pick-up allows you to enter an IP address (v4 or v6) to access a machine anywhere on the Internet and was added to allow people within a corporate intranet to access a different segment where their render machines may be sitting. It is not designed to create a global render network, although you can try.
To use the Node Pick-up function, you need to visit the NRC preferences in the NRC Controller's View menu. Go to the Nodes tab that is new to 2019.1, and turn off Use Bonjour services to discover nodes. Once done, you can check Enable Node Pick-up, which will add a new button and a new field to the NRC interface.
Bonjour on, Bonjour off
Discover Nodes uses a "well-known" port (which is the default value in prefs). If you change the port number in Preferences, you have to be sure to match it on each build slave, or you won't see anything. The Pick-Up node field can take an ip address, a range (IPv4 only) or a URL and you can add subnets with a dash (e.g. 10.38.1.110-115)
Drag and Drop Scene files
Scene files can now be dropped on the lower window in the NRC. They still need to be dragged from there to the upper window to assign them to nodes, but if you check Automatically assign newly added Scenes in the NRC Preferences then scenes will be assigned to nodes without further manipulation.