Allow External IP to pass thru so it can be seen in IIS logs

i understand you are using snat (e.g. automap, snatpool). if snat is required, you may use x-forwarded-for header to record client ip.

sol4816: Using the X-Forwarded-For HTTP header to preserve the original client IP address for traffic translated by a SNAT

Create a HTTP profile to add the X-Forwarded-For header into the request. There's an ISAPI filter you can install on your IIS server so the XFF address show up in the webserver logs