Frontier Communications Inc. agreed to expand high-speed internet access in poor communities, end an internet surcharge and improve marketing and customer service in a $60 million settlement announced Wednesday by Connecticut Attorney General William Tong.

The settlement resolves an investigation by the attorney general’s office and state Department of Consumer Protection into whether Frontier deceived or misled consumers in the marketing and sales of internet services, Tong said.

The two offices reviewed more than 1,400 consumer complaints about charges for equipment already returned, poor internet quality, unsatisfactory customer service, charges that exceeded promised rates and charges that continued after services had been canceled.

“Frontier failed Connecticut consumers. Their DSL internet quality was slow and unreliable, and their customer service was unacceptable,” Tong said.

Frontier said the settlement is primarily related to legacy DSL services and admits no wrongdoing.

“We settled the investigation in good faith to put it behind us so we could focus on our business — that’s in the best interest of all our customers,” the company said.

The settlement requires Frontier to invest in high-quality, high-speed fiber for communities without adequate internet, bringing access to 40,000 households most harmed by what Tong called the company’s “sub-par DSL service.”

Frontier has agreed to overhaul its customer service and to end a hidden $6.99 monthly internet fee that cost Connecticut families $84 last year.

Frontier must pay another $1 million to the state, and put up $200,000 to directly compensate consumers who have been wronged, Tong said.

The settlement requires Frontier to invest $42.5 million over the next 3.5 years to upgrade DSL internet service to fiber internet and that at least half of the upgrades be made in economically distressed urban and rural communities.

The agreement also provides protections for consumers who are offered the upgrade, including 45 days to decide whether to transition to fiber internet, protections against early termination or disconnection fees if cancel Frontier service, access to new customer promotional rates and information about internet subsidies through the Affordable Connectivity Program.

.