Services on First Capital Connect have been suspended between Hertford North and Stevenage due to signalling problem at Watton-at-Stone. Taxis have been arranged to transport passengers.
There are delays of up to 25 minutes on East Coast and First Capital Connect trains running through St. Neots.
Work to repair damaged cables over night is complete and all lines reopened at 6.20am this morning.
It is affecting both First Capital Connect and East Coast services between Peterborough and London King's Cross.
There are severe delays on some trains due to overhead power line problems at St Neots.
Bus replacement services are running on East Coast trains between Peterborough and King's Cross.
There are also bus replacements on First Capital Connect between Biggleswade and Peterborough.
There are also 30-minute delays on Grand Central trains.
A survey by the consumer rights organisation Which? has revealed two of the region's train companies have been ranked bottom for customer satisfaction.
First Capital Connect came bottom, with a 40% customer satisfaction rating with Greater Anglia placed just one place above in 18th scoring only 42%.
Top of the satisfaction table, compiled from responses from 7,500 regular train users, was West Coast main line operator Virgin Trains with a score of 67%. The London to Tilbury and Southend company c2c a scored 64%.
The survey also showed 40% of train travellers are likely to reduce the number of journeys they make as a result of the recent price increases.
But a third of commuters said they did not have an alternative way of getting to work and would just have to pay more.
Rail commuters in Bedfordshire, Northamptonshire and Hertfordshire will have another day of major delays.
There are delays of up to 60 minutes on East Midlands services.
First Capital Connect are warning that there are delays between Luton and London St Pancras International of 30 minutes.
Some rail commuters are facing delays of up to 90 minutes this morning.
Yesterday, major damage to overhead wires was reported.
That affected Southeastern, East Midlands Trains and First Capital Connect services.
Network Rail are reporting that trains are currently unable to run between Luton Airport Parkway and West Hampstead.
First Capital Connect has said there are delays on trains out of Bedford and Luton of up to 90 minutes.
Delays of up to an hour are also reported on East Midlands trains between Corby and St Pancras.
There are some bus replacement services in place.
There are still residual delays after yesterday's train disruption due to overhead wire problems.
There are 15-minute delays on First Capital Connect Services between Bedford and West Hampstead.
Tickets are being accepted on other services.
There are delays of up 20 minutes on First Capital Connect between Stevenage and Kings Cross, and Hertford North and Moorgate. That's due to signalling problems at Cuffley.
A replacement bus service is running on First Capital Connect between Hitchin and Royston due to emergency engineering works.
Journey times may be extended by up to 30 minutes. There is no estimate for a normal service.
There are 30 minute delays on CrossCountry services between Stansted Airport and Peterborough due to electrical supply problems at Cambridge. This is also causing problems on First Capital Connect services between King's Lynn and Letchworth Garden City.
There are also 30 minute delays on First Capital Connect services between Stevenage, Welwyn Garden City and King's Cross due to a signalling problem at King's Cross. This is also affecting East Coast trains.
There are also 40 minute delays on Greater Anglia Trains travelling between Chelmsford and London and services from Chelmsford may be cancelled.