This is a common problem with MacBook; which disconnects the WiFi once you connect a USB hub using USB3 port in Mac. I don’t understand how Apple have missed this when they built their expensive premium quality MacBook laptop. This problem was there for a long time in MacBook. The reason that I have found after doing some search was, that there are USB3 devices exist which generate radio frequency interferences and that may block the WiFi and Bluetooth signals which are operating in 2.4GHz band. Due to this interference the MacBook is unable to communicate with the WiFi. As a solution, we could take an aluminium foil sheet and wrap the USB hub cable completely as shown in following figure. Make sure the shining side of the foil paper should go inside when wrapping. This method will bring your WiFi back in your computer. Be aware, that this is the best solution that we have so far for this WiFi problem in MacBook.