The crash obviously damaged something and it hasn't quite been resolved yet.
First try some simple tasks such as:
- Go to System Preferences--> Sharing. Turn off the Internet Connection Sharing option.
- Now go to Network. Then create a new location by choosing edit location and then new location.
- Now add back in your USB Ethernet adapter interface and apply the settings. Then test your internet connectivity on your computer.
- Go back to Sharing and turn your internet connection sharing back on after choosing the Share from choice (USB Ethernet) and Share to choice WiFi.
Besides that, turn off your internet connection sharing, then go back to Network. Try editing your DNS settings on the USB/Ethernet connection and use the public IP addresses for CloudFlare and Google. CloudFlare is: 18.104.22.168 in addition to 22.214.171.124
Google is: 126.96.36.199 in addition to 188.8.131.52
Once you have the DNS settings entered and applied, test your internet connection on the computer one more time, then try turning the internet connection sharing feature back on.
If it still doesn't work, it may be a much more involved fix.
You might have luck by going to Macintosh HD--> Library--> Preferences. Drag the SystemConfiguration folder to the trash (don't empty it as you might need it again), then reboot the computer.
Your network interfaces and bluetooth settings will probably be wiped out at that point and you can try setting things up fresh.