In my SharePoint Foundation server, in event viewer we often find error
Id : 8306
An exception occurred when trying to issue security token: The HTTP request is unauthorized with client authentication scheme 'Negotiate'. The authentication header received from the server was 'NTLM'..
I configure IIS settings and Provision security token service as per this Link
One annoying thing I found with my Security Token service:
When I opened from
IIS > Sharepoint Web service > Security token service > Browse in browser I get a
HTTP Error 503. The service is unavailable. error