Et tu, Matt? While Megyn Kelly’s had a rocky start to her hour of “Today,” co-star Matt Lauer doesn’t seem to be defending her.

When an industry insider remarked to Lauer last week that celebrities are being advised to avoid Kelly’s “Megyn Kelly Today” — amid ratings struggles and awkward snafus with famous guests — a Page Six spy overheard Lauer reply that he “gets it,” adding, “It’s a big problem for them,” meaning Kelly’s show. Insiders were stunned that the veteran “Today” host didn’t try to defend his new colleague.

We’re told publicists have been steering their clients to other shows, partly because of Kelly’s ailing ratings and partly because of the dust-ups with Jane Fonda and Debra Messing. In September — just two days into her run as host of the 9 a.m. hour of “Today” — Kelly upset Fonda by bringing up the actress’ plastic surgery past.

Messing said that she “regretted” appearing on the show after an awkward moment during which Kelly asked a “superfan” audience member, “Is it true that you became a lawyer, and you became gay, because of [co-star Eric McCormack’s character] Will?”

Another reason that Hollywood flacks are booking clients elsewhere is that Kelly is struggling to hang on to viewers. As Page Six recently reported, her numbers are nearly at an all-time low for the famed NBC morning show and she continues to drag down “Kathie Lee & Hoda.”

“This week was the lowest Kathie and Hoda have rated since 2010,” said a source. “It keeps getting worse. Megyn is killing them. It is a real problem and no one wants to book Megyn’s show,” the insider said. Another source added, “They can keep telling you about all the lunches they’re taking her to, but it’s not helping the ratings.”

But a rep for “Today” downplayed any drama, telling us: “Sounds like a few troublemakers are trying to stir up drama where there just isn’t any. Everyone’s doing just fine at the ‘Today’ show.”

NBC crowed this week that “Today” “was the No. 1 morning show outright, topping ‘Good Morning America’ in total viewers and all demos last Monday.”