A solar storm like the Carrington Event could knock out the Internet
www.astronomy.com
A geomagnetic storm on the scale of the Carrington Event could potentially knock out the backbone of the Internet.

Spoiler - though they were both G5 storms, they weren’t really that comparable.

Also, big as the Carrington Event was, it’s likely it was absolutely dwarfed by one about a millennium ago, the Miyake Event