Why does it make your internet connection turn off and on?

Assuming you are on a wireless network, it is usually due to network interference. This is from wireless phones, microwaves, baby monitors, and other wireless devices. If you have a dual band router that offers a 2.4Ghz and 5Ghz, create a 5Ghz only network and connect to it. The 5Ghz band is less likely to have interference.