Under the overall settings for the Esxi server,
1. Click on Configuration Tab and Networking under Hardware
The below should appear. It should have a virtual Machine Port Group that has the appropriate name and also be tied to the correct virtual appliance and correct physical adapter.
The setup under the specific appliance should be as follows
2. Edit Virtual Machine Settings->Network Adapter 2
3. Make sure that it is is Connected under device status, and that there is a label as defined in above Virtual Machine Port Group in picture above.
In this example Appid-Mirror2 is used.
4. If the vSwitch is missing the adapter settings (ie Appid-Mirror2) and label, this will need to be added back in. Once that is done, and you return to this window, the Network Label will be blank, but you should be able to select it and hit OK to save.