Thanks for your question. I'm sorry to hear about that connection issue. It must be very frustrating. It sounds like you are already performing a lot of the basic troubleshooting and testing that I would normally recommend. That being said, if you are able to do so I might also recommend temporarily disabling your filtering (or having your Filter Guardian do so if you are unable) and then uninstalling the network extension to see if that clears the issue. In case it would be helpful I am including an article that walks you through how to disable your filter on an account level. You can find that article here43.
I might also recommend giving us a call or chatting with us in order for a more in depth investigation. After speaking with some of my techs they would also be interested in grabbing some logs off that Mac, if you'd be willing. Our Member Care Team is available at 989-720-8000 and chat is available on our website.