The fault is apparently in a new private Wi-Fi network the NFL installed in stadiums this year to great fanfare. Internet service is erratic, making a system financed by one of the world’s richest sports leagues little better than the one at your local coffee shop.

The tablet computer in his left hand — a high-tech replacement for the black-and-white printed pictures coaches have used for decades to review plays — kept losing its Internet connection, leaving Belichick unable to exchange images he and his coaches rely on to make in-game adjustments.

During the Patriots’ season-opening loss in Miami Sunday coach Bill Belichick was clearly frustrated, and not just at missed tackles and errant passes by his players.


“It’s probably less dependable than the [printed] pictures,” Belichick said in a briefing Wednesday.

This is not what the NFL was hoping to hear after it announced a $400 million sponsorship with Microsoft Corp. last year that included providing the company’s Surface tablets for coaches to use in their sideline game-planning. The system immediately encountered problems during the preseason, with other coaches, including Doug Marrone of the Buffalo Bills and Mike Smith of the Atlanta Falcons, complaining about coverage flickering in and out.

On Wednesday, Belichick said those issues carried over into the regular season.

“I’d say every game that we’ve used them in there have been times where it works fine. There are other times where you lose the connection and you don’t have it,” he said. “I’m sure that’s probably true of most other teams, too. At least other coaches that I’ve talked to made the same type of comments.”

The NFL itself has suggested its stadium Wi-Fi could be susceptible to radio frequency interference in certain places, including Miami. In August the league’s chief information officer, Michelle McKenna-Doyle, told the Sports Business Journal that network outages during a Patriots preseason game in Washington had been caused by a nearby National Weather Service facility. She added the Dolphins’ Sun Life Stadium could be a trouble spot because it is close to several TV stations.


Bill Belichick reacted to a call on Sunday. Like other coaches, he uses an NFL-supplied tablet during the games. Rhonda Wise/EPA

Yet when asked about Belichick’s gripe this week, NFL spokeswoman Joanna Hunter insisted the league’s new system worked fine during the Pats-Dolphins game.

“We had no sideline Wi-Fi connectivity issues on either sideline in Miami on Sunday,” said Hunter, adding that the NFL will “continue to monitor connectivity and address any issues as they develop.”

A Dolphins spokesman said the team’s coaches reported no problems.

With service interruptions rendering their tablets useless at times, Patriots coaches could be seen reverting to the old system of printing aerial photos on the sideline and filing them in three-ring binders. Printers remain in place as a backup, though Belichick said they have been known to malfunction.

The NFL maintains strict control over the tablets and Wi-Fi network, leaving teams with little ability to ensure signal quality in their own stadiums. Belichick has said the team experienced problems with the NFL’s Wi-Fi network in every preseason game, including two at Gillette Stadium. Their home opener is Sunday, Sept. 21, against the Oakland Raiders.

There have been no published reports of problems at TCF Bank Stadium in Minnesota, where the Patriots play the Vikings this Sunday, and the team said it does not know of any problems. The Vikings were on the road for Game 1.


Teams have no access to the tablets during the week, leaving no opportunity for tampering, upgrading — or testing — before game day. League officials distribute 25 to each team before kickoff, then collect them after the final whistle.

The stripped-down tablets are supposed to be foolproof. They don’t even have Web browsers, and their built-in cameras are disabled. They are for photo viewing only.

Hunter says the NFL coordinates signal frequencies with the clubs to avoid conflicts with other wireless networks in their stadiums, but all tech support is handled by the league.

When it does work, the new NFL Wi-Fi network is pretty slick. Even Belichick, who likes to joke that he’s tech-averse, gives it high marks. Instead of black-and-white printouts showing a defensive breakdown or a botched blocking scheme, coaches can review high-resolution color images of plays instantly on the tablets; they can zoom in and out, write notes, and quickly scroll through photos from earlier in the game to look for patterns.

The NFL’s wireless network for the Surface tablets is different from the ones many teams, such as the Patriots, have installed in stadiums for fans to use. Enterasys Networks of Salem, N.H., outfitted Gillette with a Wi-Fi system in 2012, which enables fans to stream replays — and live TV of other games — on their smartphones.

That network has been mostly reliable. Norman Rice, senior vice president of corporate development at Extreme Networks, which acquired Enterasys last year, said it is difficult to get a wireless network to work dependably inside a crowded stadium.


“You have thousands of people with thousands of devices doing thousands of things in a concentrated area,” Rice said. “One of the things that makes wireless very complex is signals get deflected by liquid, so when you put people with beverages into a venue, it exponentially complicates the challenge. Plus, it could be raining, snowing, or 100 degrees.”

The partnership with the NFL hasn’t worked out ideally for Microsoft, either. Coaches, players, and TV announcers have repeatedly referred to the Surface tablets as iPads — the product made by rival Apple.

Callum Borchers can be reached at callum.borchers@globe.com.