Product:
Planning Analytics 2.0.7
Cognos Analytics 11.0.x
Microsoft Windows 2012 server

Problem:
During change of CA11 server, you can not login to TM1 Architect or TM1WEB.
You get error: SystemServerClientNotFound
The new windows IIS for the Cognos BI gateway server is using HTTPS.

Solution:
Inside tm1s.cfg file ensure the values for IntegratedSecurityMode=5 point to correct part of Cognos Analytics.

ServerCAMURI=http://caservername.domain.com:9300/p2pd/servlet/dispatch
ClientCAMURI=https://caservername.domain.com:443/ibmcognos/bi/v1/disp

If the Cognos BI dispatcher also uses SSL, then set it up like this
https://www.ibm.com/support/pages/how-configure-planning-analytics-connect-ssl-secured-cognos-dispatcher

More Information:
https://www.ibm.com/support/pages/configure-tm1-cam-authentication-using-cognos-analytics-110-sso