VMM Host status stuck in "Needs Attention".

I have a few server in my environment on which VMM agent is installed. When I check the Host status of some of the server among them, they are showing as  "Needs Attention". I tried refreshing the host and VMs. Even I re-installed the VMM agent but with no help. Error messages on them are listed down below. 

1. WinRM issue: Error code-20506.

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For one server overall status is showing as OK in the VMM console. But still not able to resolve the "Needs Attention" issue. 

Someone please help me in sorting this out.

Thanks in advance :)

Regards,

NG