Actually - - - - it doesn't - - - - - please read the message !(There are 2 lines missing from the message that I see - - - - compared to the one that's included in the manual under 'install'.)If I don't use the USB adapter I don't have a second ethernet port so its sorta necessary - - -yes?
You don't 'need' 2 adapters.If you have a vlan capable switch you can use a vlan for either WAN or LAN. Or both.