USB Ethernet adapter not populating in settings To say that it isn't being detected seems incorrect.

$ ioreg -p IOUSB -l -w 0
...
+-o USB 10/100 LAN@14200000  &lt;class AppleUSBDevice, id 0x10000ee80, registered, matched, active, busy 0 (13 ms), retain 11&gt;
  |     {
  |       "sessionID" = 176409708174141
  |       "iManufacturer" = 1
  |       "bNumConfigurations" = 2
  |       "idProduct" = 33106
  |       "bcdDevice" = 8192
  |       "Bus Power Available" = 500
  |       "USB Address" = 11
  |       "bMaxPacketSize0" = 64
  |       "iProduct" = 2
  |       "iSerialNumber" = 3
  |       "bDeviceClass" = 0
  |       "Built-In" = No
  |       "locationID" = 337641472
  |       "bDeviceSubClass" = 0
  |       "bcdUSB" = 528
  |       "USB Product Name" = "USB 10/100 LAN"
  |       "PortNum" = 2
  |       "non-removable" = "no"
  |       "IOCFPlugInTypes" = {"9dc7b780-9ec0-11d4-a54f-000a27052861"="IOUSBFamily.kext/Contents/PlugIns/IOUSBLib.bundle"}
  |       "bDeviceProtocol" = 0
  |       "IOUserClientClass" = "IOUSBDeviceUserClientV2"
  |       "IOPowerManagement" = {"DevicePowerState"=0,"CurrentPowerState"=3,"CapabilityFlags"=65536,"MaxPowerState"=4,"DriverPowerState"=3}
  |       "Device Speed" = 2
  |       "USB Vendor Name" = "Realtek"
  |       "idVendor" = 3034
  |       "IOGeneralInterest" = "IOCommand is not serializable"
  |       "USB Serial Number" = "84E714001EAD"
  |       "IOClassNameOverride" = "IOUSBDevice"
  |     }


But, see screenshots below:




I have no options to configure/use the device.
It is made by c2g

c2g.com/uk/product/81672/usb-2.0-to-fast-ethernet-adapter
You are probably missing a driver for the device. One is available here: USB 2.0 To Fast Ethernet Adapter -> Support. I don't know if it works though because the driver is very old (2008)!