Use the solution of @Gormo, worked for me in AX88179 UGreen ethernet dockstation. https://developer.apple.com/forums/thread/651132

I found a blog from "David Hamann" - "Sharing a VPN connection with another device on macOS Sierra/El Capitan" (I cannot add a link here, so it's better later google it), where you can find an explanation to share a connection from tunnelblink. Answering your question, you can revert using: $ sudo pfctl -e $ sudo pfctl -F all