WASHINGTON — As a lobbyist for the cable and wireless industries, Tom Wheeler played a role in shaping almost every major telecommunications policy and innovation over the last three decades.

Cable and telephone deregulation. Internet service in schools and libraries. C-SPAN.

None of them, though, have generated as much public interest as net neutrality, the policy most likely to define his time as chairman of the Federal Communications Commission.

In the last few months, Mr. Wheeler’s guidelines for net neutrality, the concept that users should have equal access to any legal online content, have become a lightning rod for criticism. More than 3.7 million comments about the policy have flowed to the commission. Many of them argue that Mr. Wheeler’s plan does not go far enough to protect an open Internet.

Underlying much of the criticism has been Mr. Wheeler’s long history as a lobbyist or investor in companies he now regulates. But almost a year into the job, Mr. Wheeler has established a record as a formidable opponent to the industries he used to represent.