Thanks for posting your question here, we’ll be happy to help. First, let’s try and figure out where the failure is occurring when you reconnect the USB ethernet adapter. It’s likely one of two things, either the operating system is failing to recognize the adapter and match up the correct driver or the adapter is failing to get an address from the network.
Start off with the adapter working. If you click on the Apple Icon in the upper left corner of your screen, and select “About this Mac” and then “More info…” and then “System Report” and then look under USB you’ll an entry for the AX88178.
Select the AX88178 in the USB Device Tree window and copy or otherwise take note of the details listed for the device. We’ll want to know the BSD Name for troubleshooting.
Next select “Extensions” from the Software list on the left. Find the entry for AX88178 and copy the information there as well.
Then start a terminal and type ifconfig. Find the interface that is listed with the BSD Name from above. This is the USB to Gigabit ethernet adapter, note it’s address.
Now, unplug and re-connect the device.
We’ll want to repeat the steps above and see what changes. Particularly, we’ll want to see if it’s getting assigned and address as in the ifconfig command above.
If so, look in the System Information screen under software for the location and see that it matches what was there before. It should read something similar to /System/Library/Extensions/IONetworkingFamily.kext/Contents/Plugins/AX88178.kext .
Let me know what you are seeing and we’ll figure out our next step.
Thanks for your patience,