UPDATE, 1.30PM: V/Line's chief executive officer says the network-wide shutdown of train services on Wednesday morning was unrelated to two previous shutdowns of train services.
V/Line has suffered major shutdowns three times in the past five weeks, resulting in thousands of people unable to use train services.
Although the latest error was down to a "communications fault", like the previous shutdown on May 18, V/Line CEO Matt Carrick said the two incidents were unrelated.
"The major problem that we had a number of weeks ago was in relation to a damaged cable in a data centre," he told 3AW.
"The advice I have is that this is a different problem to do with the firewall, so effectively the security blanket...and is totally unrelated to the incident a couple of weeks ago."
The trains have now all returned to normal.
EARLIER, 9AM: The Shadow Public Transport and Roads Minister Steph Ryan is calling on the state government to give a full explanation on why V/Line trains have been cancelled for the third time in five weeks.
There were major delays and cancellations on the V/Line network statewide due to a communications fault on Wednesday morning.
But Ms Ryan criticised the state government for not providing further information on how a fault such as this can shut down the network.
"Anybody travelling from Victoria's key regional centres couldn't get to work today, to critical medical appointments, to business meetings, but all the government offers is a lame excuse that this is a 'communications fault'," Ms Ryan said.
She said regional passengers were realistic and knew there will be delays and cancellations at times but also deserve to know more information to understand why such widespread disruptions were happening.
"This is a source of endless frustration to regional people and we should be able to expect a train is going to turn up and get us to where we need to go on time," she said.
"It's clear the network is ageing [and] it's clear it needs additional investment."
Train services started to resume later in the day, but there would be ongoing delays.
"Following a communications outage which resulted in a suspension of V/Line services, a temporary fix has been found to allow trains to resume across the network," a spokesperson from the Department of Transport said.
"Significant delays are likely throughout the morning as services get back into position for the normal timetable.
"Some services may be replaced by coaches."
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