You lose network connectivity when you delete a port group associated with the iBFT network adapter.
A loss of network connectivity occurs after you delete a port group.
When you specify a gateway in the iBFT-enabled network adapter during ESXi installation, this gateway becomes the system's default gateway. If you delete the port group associated with the network adapter, the system's default gateway is lost. This action causes the loss of network connectivity.
Do not set an iBFT gateway unless it is required. If the gateway is required, after installation, manually set the system's default gateway to the one that the management network uses.