Get IP With Different Segment Or Gateway?

I'm trying to develop local website that records and save to sqlserver the private ip of person who will login to my website, Im using Windows Server r2 as my server, Now my problem is it only records the IP with same segment of my server which is segment zero like(192.168.0.83), if the IP of user is segment 1 or 2 the only the Default gateway of their IP are being saved, Correct me if I am wrong if it is defends on segment or gateway.

Code:
if (string.IsNullOrEmpty(HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]))
{
Label2.Text = (Request.ServerVariables["REMOTE_ADDR"]);
}
else
{
Label2.Text = (Request.ServerVariables["HTTP_X_FORWARDED_FOR"]);
}