The disruption is systematic and is enforced by the Iranian government upon its people. Speculation based on leaked documents hint that this was planned to happen and war has just anticipated the Internet shutdown in a rush to silence criticism against the government. Some now fear this might be the beginning of another closed network such as China or North Korea.
Unfortunately, there is no stable solution for accessing the Internet as of now, although an underground market has emerged for VPN configs that provide access to the Intention. Due to scarcity each Gigabyte of internet is trade for 2 to 4 euros.