Originally, the NetSynth/NetFilter plugins didn't provide a custom GUI, so you were stuck with whatever generic GUI your DAW provided. This turned out to be very clumsy for entering IP addresses and port numbers.
As of the December 24, 2017 update, both the AU (Mac) and VST (Windows) plugins provide a simple GUI to specify the IP address and port number for the remote server (NetVSTHost instance).
The Windows GUI looks like this, and you enter a single string e.g. 192.168.1.100:27016, then hit Update.
The Mac GUI is almost the same, but has separate input boxes for the four IP address numbers and the port number; otherwise, it works the same.