Today, we have 3 ESXI servers in version 6.5 hosted at Online. For several weeks, for no reason, we have been experiencing the same problem on 2 ESXI. The network adapter on our local card ( Private network) no longer wants to connect to our various virtualized machines via ESXI.
The problem is present on old virtual machines (Ubuntu, CentOS,...) as well as recently created machines.
On one of the 3 ESXIs, we have a DHCP that must assign IPs to the other VMs of the other ESXIs.
I remain at your disposal for any further requests.
Please help us understand your environment and throw more light here: