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.

If you have implemented or planing to implement the "URL Preview" feature for HCL Connections, make sure you import the Root Certificate for "Let’s Encrypt" certificate authority inside the java trust store. By default, the root certificate of "Let’s Encrypt" certificate authority is not in the java trust store which the HCL