All requirements for the server access and server installed components have been validated. The connection to the server fails from a Connector client which is known to be working properly.
File permissions within the Project Insight installation folder may not be set properly to allow the Connector applications access. Using the reference from the installation instructions, set "Everyone" to "Full Control" in the Project Insight folder (the default is \Inetpub\Project Insight) and replace permissions on all child items
If anonymous access in IIS has been disabled it may be necessary to set "Enable anonymous access" on for the "Office" subfolder in the IIS settings for the Project Insight Web site. This setting is anonymous by default when following the standard installation instructions for Project Insight, but may have been changed if Windows authentication was configured in IIS for accessing the Project Insight Web application as opposed to using the standard Web-based login method.