Remote Server Health status shows as "Critical" even if the server is online and working fine

There are 2 servers in the network with an hourly Replication enabled. There is a scheduled Site Status report everyday at a fixed time. Most of the time customer is getting Site status of ServerB as 'Critical' and the reason shows as 'A server was offline.'

Whereas they have observed that the Site was online and working normally.

Best,
Aniket