Seeing an error displayed as "WAN Port "CUSTOM_PORT_NAME" references Overlay Hub Endpoints that do not exist"

Navigate to your wan Edge config for the site showing the error

Find the WAN interface "CUSTOM_PORT_NAME" and open the side pane

Observe: This may only occur if WAN interface "CUSTOM_PORT_NAME" is in "override template settings" mode. (notice override checkbox at the top of the interface settings)

Scroll down to the bottom.

You'll see one Overlay hub endpoints with "none" , delete this row.