Chronicle Country rail passengers are being urged to find alternative routes home from London due to ongoing problems on the Great Northern route.
Services between London Kings Cross and Arlesey, Biggleswade and Sandy are affected.
First Capital Connect has increased its usual offer of compensation to affected passengers as a result.
The usual evening peak restrictions have also been lifted, while first class has been declassified.
Phil Verster, route managing director for Network Rail said: “We apologise for the disruption to passengers. This was due to a fault in the signalling system between Alexandra Palace and New Barnet.
“Our engineers have been out on site since early this morning and are working to fix the problems as soon as possible. An investigation into the root causes of the failures is also under way.”
First Capital Connect customer service director Keith Jipps said: “It has been a very frustrating day for our passengers and staff. We have done our best to help but the signalling system also knocked out many of our station information and online systems which made a difficult situation even harder.
“We brought in buses, sent out extra staff to stations and arranged for our passengers to be able to use their tickets on other operators’ services. “However, the severe impact of this large signal failure could not be avoided.”
He added: “In recognition of the extremely difficult journeys our passengers have had to endure this morning, we have increased the compensation we normally offer so that it covers the full fare if they were delayed by 30 minutes or more, rather than the 50 per cent normally offered for delays between 30 minutes and an hour.
“The continued failure of the signal system means our evening service is bound to be affected even if repairs are finished soon and we are recommending our passengers seek alternative transport and travel home early.”