I'm getting the client IP address to determine whether the client is on our corporate network, and changing the content accordingly. This is better in this case than having separate internet and intranet sites. It works fine on dev and test, but on the production server the IP address comes through as 172.16.4.8 when the client is on our network. I assumed at first that that was the proxy server, but now I see that everyone is set to bypass the proxy when the site is one of ours, and I learned that that address is in the reserved private address space. This explains why when I go to sites such as whatsmyip.org they show my address correctly - I'm going through the proxy in that case and presumably the proxy is passing my address through x-forwarded-for. I get no x-forwarded-for coming through on my site, but that's because I'm not going through the proxy.
I tried changing my settings to go through the proxy even for our own sites ...
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