It had been a pretty tranquil training camp for the Jets until adversity decided to visit Florham Park. Suddenly, with the regular-season opener a little more than two weeks away, the Jets defense has hit the type of turbulence that could impact its launch into the 2019 season.

The announcement late Wednesday that backup outside linebacker Brandon Copeland has been suspended for the first four games for violating the league’s policy on performance-enhancing substances added to the questions surrounding a now vulnerable defense.

Copeland, who is entering his seventh season, played in all 16 games last year, starting 10 and recording 35 tackles and five sacks. His suspension comes the same week the Jets learned they’ll be without starting inside linebacker Avery Williamson for the season after he tore his ACL playing with the second team in the Jets’ preseason game at Atlanta on Saturday.

That isn’t the Jets’ only concern on defense. Cornerback Trumaine Johnson remains sidelined with a pulled hamstring with no indication if he’ll be ready for the Sept. 8 opener against Buffalo. Meanwhile, safety Marcus Maye only returned to full duty this week, having been out since November with a shoulder injury.

At a time when defensive coordinator Gregg Williams should be fine-tuning his personnel heading into the third preseason game against the Saints on Saturday at MetLife, the Jets defense is trying to find pieces.

Copeland’s suspension perhaps explains the Tuesday signing of linebacker Stephone Anthony, a former 2015 first-round pick of the Saints. Anthony spent the past two seasons in Miami playing for Adam Gase, appearing in 24 games.

“He fits into our locker room well,” Gase said. “He knows a little bit of our defense. It’s different than what he’s been in, but at the same time there’s similarity to what he did when he was younger. He’s got a couple of weeks to see where he fits in.”

Neville Hewitt figures to replace Williamson, who posted a career-high 120 combined tackles last year after signing a three-year $22.5 million deal as a free agent. Hewitt, undrafted in 2015, played three seasons with the Dolphins.

The Jets will also take a hard look at Harvey Lang, a former Patriot, who spent most of last season on the Jets practice squad, and rookies Jachai Polite and Jamey Mosley. Polite is the third-round draft choice after collecting 11 sacks at Florida.

None of the candidates figures to offer the type of production expected from Williamson and, to a lesser extent, Copeland. But Williams is already molding the Jets to believe in the “next-man-up” mentality by teaching concepts rather than exclusive positions.

“It’s mandatory that everybody has a second position they have to learn and some guys have pushed on to a third position,” Williams said recently. “That’s how you battle injuries because it’s next man up.”

Copeland took to Instagram to explain his positive test for PED, saying, he was “taking a supplement AFTER multiple verifications that it was safe for me to use.” He said the supplement was “contaminated with a banned substance — NOT on its label.”

The Jets should feel fortunate quarterback Drew Brees and the high-powered Saints offense are only here for a meaningless preseason game. Had this been a real game, Williamson’s injury and Copeland’s suspension would have been devastating. Now the Jets have a little more than two weeks to get their unit healed and ready.

“Once we get into the regular season, it’s about playing the guys we have,” Williams said. “I’ve been doing it for 40 years, so that’s how it is.”

Next Man Up sounds great in theory, but the Jets can’t keep losing defensive players at this rate and expect to be ready for the Bills.