Sydney Trains back on track after 'network-wide communication issue' caused chaos

Most Sydney train lines have returned to normal while some are still struggling after a short-lived "network-wide communication issue" caused delays for several hours.

The T5 Cumberland line is still experiencing significant delays, with commuters being told to change lines at Granville Station for easier travel.

The T7 Olympic Park line is also still affected, with trains running every 20 minutes instead of the usual 10.

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The T9 North Sydney Line is still experiencing changes and delays.

The rest of the Sydney lines have returned to normal.

The issue, the exact nature of which is unclear, prompted the network to warn passengers that the current timetable may not run as expected.

"Please allow plenty of extra travel time due to a network-wide communications issue earlier," Sydney Trains wrote on X, formerly Twitter.

"Trains may be stopping at different platforms and journey times may take longer."

The NSW TrainLink North Line is also still experiencing delays. The South and West TrainLink lines have returned to normal.

Passengers are being urged to expect delays and to use transport apps for updates.