Nearly half the Australian population were left without internet or phone service on Wednesday when Optus crashed. Coming just over a year after the telecommunications provider was embroiled in the worst cyber breach in Australian history, the company has once again been widely criticised for its response. Laura Murphy-Oates speaks to cyber expert Matt Tett and technology reporter Josh Taylor about what could have caused this outage, and what it means for the reputation of one of Australia’s biggest telecommunications companies You can support the Guardian at theguardian.com/fullstorysupport