I recently ran into an issue where our ESXi hosts runing ESXi 7.0 u3g connected to a vCenter Server running 7.0 u3g would go into a state of not responding. The Virtual Machines (VMs) would continue run on the host, but if you tried log into the host from the Direct Console User Interface (DCUI) the screen would freeze at the login screen.
If you are so unfortunate as to run into this issue, just be patient and the login will complete. It could take between 5 to 45 minutes for the login to complete but it will eventually get there.
After it loads you will need to restart the managment agent on the host by going to Troubleshooting > Restart Managment Agent. After restarting the services the host should report back into vCenter on it’s own.
To fully resolve the issue you should consider upgrading your vCenter to at least 7.0u3j which will resolve the issue.
I know this is a short post, but I really hope it helps someone out there. Please feel free to share this around to others who may need it.