Applies to: all versions
If you're experiencing ESXi connectivity issues, you should consider to restart Management Agents on your ESXi host.
The restart may impact any tasks that are running on the ESXi host but not the running VMs.
This article is also useful in case ESXi displays "Invalid user or password" or web UI are not available and SynetoOS displays "Local hypervisor is inaccessible".
Using DCUI (Direct Console User Interface)
Step 1: Connect to the console of your ESXi host, using Physical Display and keyboard or IPMI
Step 2: Press "F2" to customise the system
Step 3: Login with "root" user and your password
Step 4: Use the "Up/Down" arrows and navigate to "Troubleshooting Options > Restart Management Agents"
Step 5: Press "Enter"
Step 6: Press "F11" to restart the services
Step 7: When services are restarted, press "Enter"
Step 8: Press "Esc" to log out
Using ESXi Shell or Secure Shell
Step 1: Login to ESXi Shell or Secure Shell with "root" user
See How to enable ESXi Shell or Secure Shell for further details
Step 2: Restart the ESXi host daemon and vCenter Agent Services:
Vmware related documentation: