It is due to the problem with the JMX communication between and Admin and your OSB managed servers. Did you observed any messages related to it?
Is it a SSL communication, then try to make sure that certificates are valid.
As a general practice, make sure you have listen address configured for your servers. If left it blank(default), then it would be listening on the all the available host and communication would get messy in these situations.
If still facing problem, i would suggest you enable the below debugs and raise a support case
1. Apply the below three debug logs from console(for admin as well as Managed Server)
2. Restart all the servers
If the issue, occurs, provide the debug along with the thread dump(take 5 thread dump at an interval of 5seconds) for the Managed Server(which is unknown state) and for the admin server.
Thank you for your response.
We have listener address configured for both Admin and Manage Server.
As per your suggestion, I have enabled debug parameters on Manage and Admin server.
Whenever issue reoccurs, I will take the thread dump and will upload the logs.
Kindly keep posted your valuable suggestions.