Wahlstrom scored on a wrist shot from the top of the right face-off circle. He has three goals and three assists during his point streak.
Anders Lee made it 2-0 at 7:51 on a wrist shot at the right post. Andy Greene, who played 14 seasons with the Devils before he was traded to the Islanders on Feb. 16, 2020, had the primary assist for the defenseman's first point against his former team.
"It was one of those games that felt a little stagnant at times and I think we just really stuck with it and tried to get to our game in the third period," Lee said. "[Wahlstrom] is feeling it. I think he's a shooter that can bury the puck from anywhere and he's got some range. 'Wally's' just done a phenomenal job of stepping in, each night, building his game. It just creates confidence, and then you start putting a couple in and it rolls from there."
Wood ended Varlamov's shutout with a snap shot and Dell pulled for an extra attacker for the 2-1 final.
The Islanders limited the Devils to one shot on goal during a two-man advantage for 25 seconds in the second period with Ryan Pulock (tripping at 2:40) and Cal Clutterbuck (slashing at 4:16) in the penalty box.
New Jersey was 0-for-4 on the power play.
"That was our opportunity, the quick 5-on-3," Devils coach Lindy Ruff said. "I thought a couple of power plays, [we] moved it around quick. … There was a couple of times we didn't get the bounce we wanted. We didn't find the hole, but it was probably the difference in the game."
Varlamov made 24 saves in the final two periods, including 16 in the second.
"I thought we had pretty good poise; I didn't think we had a lot of energy tonight," Islanders coach Barry Trotz said. "I think the games piled up on us emotionally; three games in four nights. I thought our first period was fine and we really didn't give them anything.
"The second period really took its toll and it took everybody out of a rhythm, but our penalty killers were really strong and a couple of big saves from 'Varly.' We got through that [second] period and I thought we responded in the third period."
NOTES: The Devils had 10 percent of Prudential Center filled with fans (1,800) for the first time this season. … Clutterbuck had one shot on goal in 14:41 of ice time after missing two games with an undisclosed injury. ... New Jersey forward Pavel Zacha had his point streak end at 10 games (four goals, eight assists). It was the longest active streak in the NHL. ... Devils center Nico Hischier missed his second straight game with an upper-body injury.