When the months-long financial disputes between Netflix and Internet service providers ended last summer, a lot of network congestion problems that affected Internet consumers were cleared up.

But that doesn’t mean network problems, including some caused by financial disputes, are a thing of the past. They just might be a bit less widespread, and they’re definitely getting less publicity. But they have a real impact on consumers trying to use Internet service, according to the Measurement Lab Consortium (M-Lab).

M-Lab, founded by the New America Foundation's Open Technology Institute, the PlanetLab Consortium, Google, and academic researchers, hosts measuring equipment at Internet exchange points where retail Internet providers exchange traffic with Internet backbone operators.

Recent M-Lab data shows problems at interconnection points involving retail operators Comcast and AT&T and backbone operators GTT and Zayo. In some cases, the problems are more severe than the ones involving Netflix a year ago.

When contacted by Ars, AT&T, Comcast, and GTT confirmed the interconnection problems identified by M-Lab. Zayo has not provided any comment.

AT&T is seeking money from network operators and won’t upgrade capacity until it gets paid. Under its peering policy, AT&T demands payment when a network sends more than twice as much traffic as it receives.

“Some providers are sending significantly more than twice as much traffic as they are receiving at specific interconnection points, which violates our peering policy that has been in place for years," AT&T told Ars. "We are engaged in commercial-agreement discussions, as is typical in such situations, with several ISPs and Internet providers regarding this imbalanced traffic and possible solutions for augmenting capacity."

Poor AT&T connections found by M-Lab are with Zayo in Dallas, GTT in Chicago and GTT in Atlanta. The data points are from November to January, but AT&T’s statement to Ars indicated that problems are ongoing. M-Lab also found less severe congestion from back in September between AT&T and Level 3 in San Francisco.

Under the Federal Communications Commission's new net neutrality rules, companies will be able to file complaints about interconnection disputes that harm Internet performance.

M-Lab data from November also shows poor performance between Comcast and GTT in Chicago. While AT&T is seeking payment to clear up this congestion, Comcast may not be.

Comcast told Ars that the links with GTT are “settlement-free,” meaning no payment is exchanged, and that they are going to be upgraded soon. Comcast acknowledged a capacity shortage with GTT in both Chicago and Ashburn, Virginia.

“We have been in contact with GTT and are working together to increase capacity at two interconnection points,” Comcast told Ars. “We expect that process to be completed shortly and to fully resolve the issue.”

GTT offered a similarly hopeful response. “GTT has been in touch with Comcast and we are working together to increase capacity at the two intersections,” GTT told Ars. “This issue should be resolved shortly.”

Level 3 told Ars that it "cannot comment on any ongoing interconnection discussions with AT&T or any other broadband provider."

The company—which agreed to pay Comcast for interconnection after a previous dispute—said it believes payment demands would violate the new net neutrality rules.

"If Level 3 is willing to deliver Internet traffic to a broadband provider in the local market in which the broadband provider’s customers are asking for it, we believe that such a broadband provider’s demand for an access toll from Level 3 would violate the new Open Internet rules," Level 3 general counsel for regulatory policy Mike Mooney told Ars. "We also believe that if that broadband provider has congested interconnection links to the Internet and refuses to augment those interconnection links at a nominal cost, the broadband provider is not honoring its promise to provide its customers with the ability to access the Internet, as required by the Open Internet order.”

A problem caused by the industry, not just one company

M-Lab’s “Internet Observatory” lets you view download and upload speeds, and other measures like latency, for connections between network operators in Atlanta, Chicago, Dallas, Miami, New York, San Francisco, Washington, DC, and other cities.

M-Lab researcher Collin Anderson told Ars that the latest data points show that problems are more widespread than Internet service providers like to admit. The transit provider Cogent has been mixed up in a lot of the most well-known interconnection disputes, including the one with Netflix, leading Internet providers to argue that this is more of a Cogent problem than an industry-wide one.

Cogent was at the center of last year’s battles because its connections to ISPs were overwhelmed by Netflix traffic. Netflix, a customer of Cogent, was delivering traffic over Cogent’s settlement-free links with ISPs, and Cogent refused to pay the ISPs for more capacity. (Cogent exchanges traffic with ISPs without payment, but Comcast, AT&T, Verizon, and Time Warner Cable complained that Cogent was sending too much.)

In January 2014, “the download throughput rate during peak use hours for Comcast and Verizon traffic over Cogent’s network was less than 0.5Mbps,” we reported last year in an article using M-Lab data.

AT&T’s connections to GTT in Atlanta and Chicago have been even worse, going below 0.2Mbps. Comcast’s link to GTT in Chicago dipped below 0.5Mbps.

“What this shows is that there continues to be failures to properly maintain the infrastructure between the major access ISPs and the transit providers,” Anderson told Ars. “This is in line with the assertions made by transit ISPs like Cogent and Level 3 in public, but we are showing that this is occurring on networks that haven't spoken up and is more extreme than past cases.”

While these links don’t carry Netflix traffic, they carry many other types of traffic that home Internet users are likely to access. Congestion is so bad in some cases that “large sections of the Internet are nearly inaccessible for the major access ISPs,” Anderson said.

M-Lab’s data is crowdsourced, with data streams "sent from the user’s device (laptop, mobile, or other client-side gadget) to the nearest M-Lab measurement point." This system provides an accurate assessment or what an ordinary Internet user experiences, Anderson said.

“We sit behind the same interconnections as the content served by GTT and Zayo, and so the failures that we see occur for every connection that traverses those network segments,” he said. “M-Lab data is not artificial; it comes from tens of thousands of home users in the United States, so those users are exactly the people that cannot properly access the Internet.”

Like the Netflix and Cogent problems last year, awful performance at interconnection points is often a sign of a business relationship gone awry, Anderson said.

“I would suspect that given this is the core of the business and given the extremes of the degradation that it wouldn't likely be negligence, that there would be a pretty strong incentive in an ideal system for the maintenance of these links,” he told Ars.