The latest update to the EOS Utility includes the Canon UPNP Detector Program which searches for wireless connections between a Canon DSLR (6D or 70D) and your computer.  On Windows 8 and 8.1 computers that are connected by wire to a wireless router the program will cause all connected wireless devices on the network to lose their connection, signal and internet connection. 

If the computer is connected to the network through a wireless connection there is no problem.  A work around that I use consists of stopping the process of the Canon UPNP Detector in the Task Manager after reboot.