Hello.
I don't know if you have already tried the following, but it would be good to try, assuming that the physical connection is correct between the vCenter server and the ESXi hosts
Restart the vcenter server completely, check if the ESXi hosts and try to reconnect them.
enter one of the ESXi host that does not connect turn off the VMs, put the ESXi into maintenance mode and then restart the ESXi.
When the ESXi host is up again, take it out of maintenance mode and try to reconnect it from the vcenter server.
Enrique Espinel
Senior Technical Support on IBM, Lenovo, Veeam Backup and VMware vSphere.
VSP-SV, VTSP-SV, VTSP-HCI, VTSP
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