This rules out the chances that the adaptor is defective.

Tried another USB Adaptor with a Realtek chipset that used to work, but to no avail.

USB Adaptor is 100% known good - works on a Windows PC, iPad, iPhone, and another Mac.

Note how it is detecting the USB adaptor, but doesn't appear in Network Preferences. I thought I might need to delete the connection and add it again, only to find that you can't add the USB Ethernet connection in Network Preferences, as shown below. Even if I connect a cable to the adaptor, it doesn't go online in the Network Preferences panel. So no drivers are necessary, and has worked flawlessly in the past.Īll of a sudden, it would not detect the Ethernet connection at all, even though the System Information clearly shows that the 'USB 10/100/1000 LAN' is connected and working.

The adaptor I'm using is a standard USB to Gigabit Ethernet adaptor, using a Realtek chip. I'm suddenly seeing a problem where my MacBook is refusing to connect to Ethernet, despite that a known working USB to Ethernet Adaptor (Realtek chip) is connected to the MacBook.

Manhattan products usb to ethernet mac