Symptoms:
When an ESXi datastore is on a LUN device for E3 FCoE HBA (Driver is qfle3f), you see these symptoms:

• Virtual machine network traffic will be intermittent during a LUN path failover.
• Virtual machine I/O should not be affected, although some of the VM's network speed will be zero during an FCoE LUN path failover.

VMware vSphere ESXi 6.7
VMware vSphere ESXi 6.5

This issue occurs because the virtual machine's datastore is on an E3 FCoE HBA's LUN device and the LUN device has two ore more active paths. When the LUN device cannot be accessed, it will do a failover task to make sure the device can be access by another active path. If the virtual machine's I/O pressure is heavy and a failover is triggered, the VM network traffic will be intermittent during the failover process.

This is a known issue affecting VMware ESXi 6.5.x.

Currently, there is no resolution or workaround.