DALLAS — That will put a damper on the Islanders’ fledgling momentum. 

It’s not merely that the Stars snapped their five-game points streak here at American Airlines Center on Sunday night, beating the Islanders 6-3. It’s that the how of it included so many reminders of the Islanders’ limitations. 

Namely, their speed, or lack thereof. The Islanders have shown they can play around it — indeed, they did at points Sunday — but doing so requires impeccable detail and decision-making up and down the lineup. When pieces are off, when they are playing one of the league’s faster teams or both, as was the case here, it is so much harder to get away with. 

“The lesson in that,” coach Pete DeBoer said after his Dallas homecoming was spoiled, “is we can’t play that game against good teams.” 

The Stars could get pucks behind Adam Pelech and Ryan Pulock and then beat them to it. They could handle dump-ins from the Islanders’ workmanlike third and fourth lines with ease, moving the puck out before the Islanders could start their forecheck. Jason Robertson can capitalize on a split second of indecision from Brayden Schenn behind his own net and turn it into a goal. 

Put all that together and you have a steep uphill climb for the Islanders to stay in a game. 

“[The Stars] have great gaps, great reloads,” Schenn told The Post. “They take away the middle of the ice. … And then when we put it in, forwards weren’t getting first touches and forechecks, allowing them to break out a little cleaner than obviously we wanted to. We have lots to clean up and focus on.” 

To their credit, the Islanders stayed in the game, at least for a time. They fought back down 1-0, 2-1 and 3-2 to go into the last 20 minutes tied 3-3 after Schenn deposited Anthony Duclair’s feed from behind the net past Jake Oettinger at 17:45 of the second. 

What they couldn’t do, though, was change the tide of the game. And when the current picked up, the Islanders were carried right along with it. 

So 4:10 into the third, Wyatt Johnston gave Dallas its fourth lead of the night, getting open in the slot after the Islanders overcommitted to the strong side of the ice and burying one. 

This time, the Islanders didn’t have the immediate answer. Robertson floated behind Pelech and was sprung by Tyler Seguin’s pass before scoring to make it 5-3. 

Adding insult to injury, Mikko Rantanen — the arch-villain last time the Islanders played here — made it 6-3 mere minutes later. 

Ilya Sorokin, who gave up six or more goals just twice last season, finished with stops on just 32 of the 38 shots he saw, albeit without impressive defense in front of him. DeBoer said he never considered giving Sorokin the hook, saying it was more on the defense in front of him. 

Nevertheless, by the end of the night, pockets of the crowd chanted “Otter’s better.” 

“Tough game,” Sorokin told The Post. “We should be better in D zone, and [I] should be better in net, my [positioning]. Tough game. Should make a good review and get ready for next game.” 

At so many different points before the Islanders fell apart, they were on their heels. 

They didn’t record a shot for more than seven minutes to start the game. When they did notch a dangerous chance, the Stars came down the other end, and Seguin scored on the rush. There wasn’t much forecheck to speak of; rather, it was the Stars who were consistently able to get pucks in deep and get to work. 

Still, the Islanders found ways to stay in it. Matthew Schaefer turned on the jets and blew past Johnston to tie the game at one, and Palmieri made an excellent play on his backhand to tie it 2-2. Schenn atoned for his earlier error to make it a 3-3 game, but in the third, the duct-tape-and-glue approach with which they’d kept it together all night caught up with them. 

“We weren’t great,” DeBoer said. “It was Game 11, it’s the first night I felt we didn’t have great legs, great juice.”