A massive Internet outage that left many of Time Warner Cable’s 11 million customers – including 350,000 in Maine and New Hampshire – without service for several hours Wednesday morning occurred when technicians were making a routine update, the company said.

Scott Pryzwansky, Time Warner’s director of public relations, said that he couldn’t be more specific about how the outage occurred, and that the company is investigating the cause.

He described the problem as “an issue with our Internet backbone” that cut Internet service and access to the company’s On Demand video channel, although cable television and landline phone service were largely unaffected. Those with smartphones could still access the Internet.

Pryzwansky said the outage started at 4:30 a.m. and service was “largely restored” by 6 a.m. Some customers said they lost Internet access as early as 3 a.m., and others said their service wasn’t restored until 8 a.m.

Carolyn Beem, a spokeswoman for L.L. Bean, said the Freeport retailer was unable to get its site online until about 8 a.m.

The outage, which hit Time Warner customers on both coasts as well as some states in the Midwest, is a reminder that speed and security aren’t the only priorities in the online world, said the head of an Internet service provider based in Maine. “There’s also reliability,” said Fletcher Kittredge, CEO of Biddeford-based GWI.

Time Warner sent a Twitter message to customers Wednesday morning that said “we’re working to restore services to all areas as quickly as possible; no ETR (estimated time of restore). Tweets will be delayed while this is addressed.”

The company then tweeted an apology around noon, and by late afternoon was tweeting announcements about various sweepstakes the company was conducting.

On Tuesday, Time Warner Cable paid $1.1 million to resolve an investigation by the Federal Communications Commission that found the provider did not properly report multiple network outages. On Wednesday, New York Gov. Andrew Cuomo said the latest outage will be investigated by regulators in his state as part of a review of the proposed merger between Time Warner Cable, the country’s second-largest cable services provider, and Comcast, the largest.

Earlier this year, the American Consumer Satisfaction Index found that Time Warner Cable had the lowest satisfaction rate of any big cable provider. Comcast had the second-lowest.

According to the website Down Detector, which tracked the outages during the day, parts of New England, including southern Maine, the New York City area, upstate New York, Ohio, Kentucky, North Carolina, Texas and California, were among the areas where the outages were concentrated.

Kittredge said Time Warner Cable hasn’t released enough information to provide even an educated guess about the cause. He said that although large outages appear to occur regularly, “there’s no reason these things have to happen.”

Comcast had a major outage on the East Coast last fall and another in Chicago a week later. Both were blamed on a program that converts Web addresses to a digital format to allow a user to connect with a website.

Asked if customers would be given a refund or credit for Wednesday’s outage, Pryzwansky said Time Warner Cable was focused on service restoration and investigating the cause, and executives have not discussed the issue of refunds. However, he noted twice in a brief email that the outage only lasted about 90 minutes and was resolved for most customers by 6 a.m.

Beem, the Bean spokeswoman, said the outage occurred while the company was performing maintenance on its site, which was taken partially offline by design beginning about 4 a.m. Bean’s maintenance, she said, allows the site to remain open to customers to place orders, but some back-office functions are disabled and the orders are not processed right away.

Bean’s maintenance was finished at 7 a.m., but the company could not restore its updated site until about 8 a.m. because it was unable to connect with the Internet, Beem said.

She wouldn’t speculate on how many customers were affected by the outage, but noted that the company chooses times when use of the site is typically at its lowest to perform system maintenance.