Check the below kb
try to kill the PID 34033
Worst case jusr do a hard rest of one host and check if that connects to vcenter
Any info on the Build Number of vCenter and ESXi?
1. Disable firewall and check host connect back in vcenter.
# esxcli network firewall get
# esxcli network firewall set --enable false
2. If host connected back in vcenter after disabling firewall , then re-enable firewall again and monitor host.
# esxcli network firewall set --enabled true
3. if host disconnected in vcenter again , enable "VMware vCenter Agent"
Go to Host through vClient >> Select Configuration >> Go to "Security Profile" >>> click on "Edit" >> Click Check-mark on box "VMware vCenter Agent" for Port 902.
Check now host will connect back in vcenter