If you are trying to use SPNEGO as the means for authenticating HCL Notes Connections Plug-In and you run into an issue, check if “Use the alias host name for the application server” option is used on Websphere Application Server and if that is the case try turning it off.
For some reason the HCL Notes Connections Plug-In cannot use SPNEGO authentication mechanism when this option is used on WAS. You can find this setting under “Global Security – Web and SIP security – SPNEGO web authentication”.
Depending on your DNS configuration and SPN entries created, this option may be needed for HCL Connections or other applications, so make sure you test everything appropriately after changing the SPNEGO settings.
Thoughts about HCL Connections, Domino and Sametime 