You have installed Symantec Endpoint Protection Manager 11.x using a custom IIS web site. You have also configured the custom web site to listen to more than one port. If you migrate the Manager to version 12.1, the new web site will listen only to the first port.
Clients may become disconnected after migration.
Symantec Endpoint Protection Manager 12.1 uses the Apache web server instead of IIS.
If you used a custom IIS web site in IIS, it will be completely replaced with an Apache site after the migration, and additional web server ports must be configured manually.
If you used the default web site in IIS, the migration will modify the default IIS web site with a proxy that redirects IIS requests to the Apache web server; additional ports will still work correctly in this case.
To configure the Apache server in Symantec Endpoint Protection 12.1 to listen to additional ports:
Open the following file in a text editor: C:\Program Files\Symantec\Symantec Endpoint Protection Manager\apache\conf\httpd.conf
Look for the "Listen" directive, e.g. "Listen 8014" and add additional "Listen" lines underneath it, one for each additional port.
Save and close the file.
Restart the Symantec Endpoint Protection Manager Webserver service through the service control manager (services.msc). This should also restart the Symantec Endpoint Protection Manager service, which depends on the SEPM Webserver service.