Services were suspended on Eurotunnel after a power supply demerit, the cross-Channel runway operator has said.
Passengers took to Twitter to report being stuck on studies at Folkestone for more than three hours. One couple said they were waiting to go on their honeymoon.
Eurotunnel apologised and said the glitch had been resolved.
Services resumed at about 13:00 BST but some services still faced retardations of up to four hours.
The company said there was an estimated four-hour wait on retirement experiences at Calais and a three-hour wait at Folkestone.
It replied instructs needed to be put back on their schedule.
On Twitter, one family said they had been stuck on a teach at Folkestone for nearly three and a half hours.
“We impede getting conflicting intelligence from Eurotunnel, ” they said.