CenturyLink was experiencing a "disruption in service," according to the company's official Facebook page. The message was posted at about 9:45 a.m. on Tuesday.
A message posted after 3 p.m. stated service to most customers early in the afternoon. The company blamed the problem on a "core router."
CenturyLink's Vice President and General Manager Bob Brown said people in 17-states experienced the Internet outage.
Customers in the La Crosse area and some areas around Madison said their Internet service had been down since early Tuesday morning.