There are massive delays across Sydney’s train network after a communications hitch knocked out the entire network for nearly two hours on Wednesday.

All lines on the Sydney Trains network were hit with significant delays and disruptions after the problem struck about 2.45pm – with authorities unable to say for more than an hour when services would resume.

The network was at a standstill for 90 minutes, as commuters were warned of peak hour chaos due to a glitch in the network’s digital train radio system.

“Allow plenty of extra travel time due to a train communication issue,” a statement on the TripView app said.

“Trains may stop on platforms or between stations for longer than normal while the issue is ongoing. We’ll update you when we have more information.”

Just after 4pm, Sydney Trains tweeted that the network had started moving again. But it was still expected to be a difficult commute home for thousands of people on Wednesday.

Sydney Trains chief executive Matthew Longland confirmed the network had been brought down by a radio issue.

“At 2.45pm this afternoon we experienced failure of our critical train radio system across the Sydney rail network. For safety reasons, that meant we had to bring trains back to platforms so that customers could safely hop off those trains,” he said.

He said engineers tried but could not reset the radio system, meaning it had to be switched to a back-up site.

“That switching took place around 30 minutes ago. And about 15 minutes ago – at around 4pm this afternoon – trains have progressively recommenced operations across the Sydney Trains network,” Mr Longland said.

But significant delays were expected throughout the Wednesday afternoon peak, with Sydney-siders urged to avoid trains until the network was up and running properly.

Pictures circulating on social media showed big crowds waiting on platforms across Sydney throughout the afternoon, as the city endured its third consecutive day of temperatures above 30 degrees.

“All services are suspended. No trains anywhere in Sydney. Currently stuck at Strathfield,” wrote one dejected Twitter user.

Other passengers also reported being stranded at stations, or trains halting mid-journey for longer than half an hour. Elsewhere, some stations closed their roller doors or had staff at turnstiles to turn away passengers.

“I am currently stuck on the Hawkesbury river on a train from Newcastle to Sydney. The Sydney Trains network is apparently completely down. Two weeks in a row I’ve been stranded,” tweeted passenger Joshua Belinfante.

“Chaos on Sydney Trains. Not surprising … if you can, give up, go have an afternoon beverage at the closest watering hole. Oh wait, we can’t afford that midweek drink anymore,” wrote another Twitter user.

The fallout has also hit other transport in the harbour city, with buses reportedly jammed and rideshare fares skyrocketing due to surge pricing.

“Sydney trains this afternoon are at a standstill. Uber fares, however, are not. Uber fare usually $20. Currently $216,” tweeted one stranded Sydney-sider.

“Good work Sydney transport. All trains are down and the only bus that takes me to where I parked is running at a ‘reduced service’,” tweeted another.