Hi Please find the below thread for best answer.
https://www.symantec.com/connect/forums/sepm-1216-ru6-mp1-program-cannot-display-web-page
Home, Monitor and Reports tab becomes blank if SEPM has 5 NICs enabled
Fix ID: 3754931
Symptom: If Symantec Endpoint Protection Manager uses more than 5 NICs (5 IPv4 or 5 IPv6 addresses), when you log on to Symantec Endpoint Protection Manager using the server name, the Home page appears blank.
Solution: Added support to Symantec Endpoint Protection Manager to allow log on into Symantec Endpoint Protection Manager, even when there are more than 5 NICs (IPv4 or IPv6) configured on the computer.
https://support.symantec.com/en_US/article.INFO3057.html
Kindly let me know if anything i can help you.