In the Julia Roberts move "Leave the World Behind", they mention a process of destroying a country. (I vaguely recall that the process was attributed to a real person.) One of the steps was to take down the internet. With lack of information chaos develops, and the country destroys itself.
i feel like taking down the internet is harder than it sounds. you could easily disrupt satellite, but the world will route around this... its actually designed for it.
they would have to poison dns or major routing points somehow.
Cut communication trunks to knock out the internet in wide areas should still be an option since storms cause those outages for non-wireless internet now. DDOS and other atracks can still overwhelm wireless communications.
But honestly it is unlikely that being technically possible would be as successful in practice as a widespread attack as most places have a lot of redundancy built in because these kinds of threats have been around for decades.