After Detroit’s Stan Van Gundy — one of just a couple of men in the NBA to serve as both general manager and coach — had advised the Nets to hire a general manager before a coach, they appear intent on doing just that. They have had cursory dialogue with at least one candidate, and asked permission to talk to at least three.

A source told The Post the Nets have reached out to Washington to request permission to interview Wizards senior vice president of basketball operations Tommy Sheppard.

They also have asked for — and received — permission to talk to Denver’s Arturas Karnisovas and Houston’s Gersson Rosas. NetsDaily broke the Karnisovas story, while ESPN was the first to report of the interest in Rosas. Both are considered viable candidates, as is two-time NBA Executive of the Year Bryan Colangelo.

Sheppard’s responsibilities in Washington include salary-cap management, negotiations, draft preparation and talent evaluation — pro and college, domestic and abroad. Though the Wizards came into Wednesday just 21-25, they did win 46 games and reach the Eastern Conference semifinals last year with a young roster that boasts John Wall, Bradley Beal and Otto Porter.

The veteran executive has been on several teams’ shortlists recently, with Memphis denied permission to talk to him two years ago.

Rosas, the Rockets’ executive vice president of basketball operations, has been with Houston for over a decade. He briefly left in 2013 to become the Mavericks’ GM, but came back that same year. Rosas worked with Jeff Van Gundy and Tom Thibodeau, something that only can be considered a plus.

“I don’t think you can hire [a coach first],’’ Stan Van Gundy said this week. “If you’re going to hire two people, you can’t hire the employee before the boss. That just doesn’t make any sense to me. And that’s immediately going to create tension, right there, the guy that’s your boss, that you report to, didn’t hire you. … So if you’re going to hire two, to me you’ve got to hire the GM first. He’s got to have say in who he has as a coach.’’

Which is why it’s a plus Rosas has a relationship with Thibodeau, a top target for the Nets and one of the best coaches available.

It’s unclear the pecking order among the Nets’ candidates. But sources said they’re quite serious about Colangelo, 50, Karnisovas, 44, and Rosas, 37 — the last two first mentioned in a Yahoo Sports report. A separate source said Ferry is “not a viable candidate” and painted Kentucky’s John Calipari as unlikely but always possible as long as he has such avid support from Nets CEO Brett Yormark.

The Nets have had Tony Brown serving as interim coach and assistant Frank Zanin ostensibly in charge of personnel since owner Mikhail Prokhorov fired Lionel Hollins and reassigned GM Billy King on Jan. 10.

In addition to Thibodeau, Calipari and fired Cleveland coach David Blatt are considered candidates. Blatt knows Prokhorov and has been stumped for by Sergey Karasev, but one has to wonder how LeBron James’ seemingly dim view of his former coach would hurt Blatt’s ability to lure top free agents, and if that would impact the Nets’ thinking.

What Prokhorov was clear about was it’s vital that coach and GM have a certain synergy that was lacking in the last duo.

“When you have two guys, the challenge is that you really have, as my owner [Tom Gores] says, you really have a synergy between the front office and the playing court, and you’re on the same page,’’ Stan Van Gundy said. “That’s obviously a bigger challenge and always will be with two people other than one.’’