Getting the IP Address of client connected over RD Gateway

Hi.

I'm trying to get the external IP Address of clients connected over Remote Desktop through a RD Gateway.

I can get the IP Address using WTSQuerySessionInformation if I'm not connected through the gateway, but I get nothing but 0's when I connects through the gateway.

Interesting moment that if I connects from Mac OS (Microsoft Remote Desktop for Mac OS),

WTSQuerySessionInformation gets client's IP normally.

Is there some other way to get client's IP? Or how to get Windows client's IP connected through RD Gateway with WTSQuerySessionInformation?