could not open a connection to the ESXi host complete fail . unable to run grab

Hello, thanks for choosing Dell and welcome to our community.

I also have private messaged you https://www.dell.com/community/en/direct-messaging

What you need to do is work with your network team "The client machine must have HTTP access to the vCenter."

They can do packet capture and see if traffic is getting blocked.

and if you believe that you have no network issue you can alwyas raise an official case through  https://www.dell.com/support/incidents-online/en-us/contactus/dynamic depending on the license source or warrant entitlement, ESXi support team from our side can help with resolution.

Respectfully,