A failed valve at a meter station has been blamed for cutting gas supplies to 9000 properties in Mt Gambier, in South Australia's southeast.
Supplies were cut on Wednesday but are being progressively restored on Friday.
All customers are expected to be back online by Monday.
Epic Energy said it appeared the valve failure created a blockage that disrupted gas flows.
"Local support attended to investigate but couldn't resolve the issue, so Epic Energy's specialist technical staff were dispatched from Adelaide on Wednesday night," the company said.
"Yesterday they identified a problem, cleared the blockage, and replaced the internal parts of the valve in their entirety so that gas flow could be restored."
The company said its team had also extensively checked all components of the meter station to enable safe operation.
The station is the endpoint of Epic Energy's South East Pipeline System, which delivers gas into the APA network.
As part of restoring the network, APA Group representatives will visit each property in Mt Gambier to help customers reignite gas appliances.
Those not home will be left instructions on how to do the job themselves or on how to seek assistance.