If you are working on a VMware vCenter Server v5.5 in an environment that has multiple segregated VLANs designed to isolate certain types of traffic, and find that the web client for your admin-facing interfaces keeps redirecting to an internal isolated IP address – and therefore fails – here’s the solution.

Edit the file C:\ProgramData\VMware\VMware VirtualCenter\proxy.xml and update the vim.ProxyService.RedirectSpec entry at ID 21, on approximately line 93. It’s the hostName value, and it will be set to one of the isolated IPs. Just change it to the new value and restart the VMware VirtualCenter Server services. Use a tool like Textpad because of the typical carriage return concerns with non-Windows-sourced files.

Voila! Problem solved.