NX (v. 3.5.0) requires an average of 40 kbps (kilo-bits per-second) to let users run a remote Windows RDP session comfortably. This is more or less the bandwidth provided by a 56 kbps modem. RDP session through NX can be run on much slower links, like 9.6 kbps GSM connections, but in such network conditions users can experience a noticeable lag.

For more information on this topic and for hints on how to determine the number of clients that can be supported over a single network connection, please refer to the following article:

https://www.nomachine.com/AR12B00119