In spite of its (historical) name, 3GW counts all kinds of mobile internet connections: 4G (LTE) / 3G+ / 3G / 2G (Edge) / GPRS, as soon as they are counted by the phone itself (the app. relies on the phone counters). The name “3G” is just a generic name for mobile data connection types.
Prior to 0.33.0 (free version) and 1.7.0 (Pro version), 3GW was not counting Wifi usage, because it’s usually free, and the purpose of the application being to help you to manage limitedresources, it focuses on handling mobile data usage in the best way it can.
However simple Wifi monitoring has been introduced in free 0.33.0 and pro 1.7.0 to help you evaluate the traffic corresponding to some usages without having to actually consume it. This support is very limited, no alerts, no prediction, no graph, it just counts.