‘RHOBH’ Star Diana Jenkins just got a BIG green light in her hunt to find who was behind a racist Instagram attack — a judge has granted her the ability to subpoena Meta, so she can hopefully identify the user who targeted her costar Garcelle Beauvais‘ son.

Court docs, obtained by TMZ, reveal the judge is allowing Diana to issue a subpoena to Meta and seek info they have on the accounts that recently sent hateful and threatening social media messages to Garcelle’s 14-year-old, Jax.

As we reported, Diana was accused of instigating hate towards Garcelle’s kid while the feud between them on the show was raging.

Diana denied any association with the comments, and even filed a lawsuit this month against the anonymous person or people she claims are behind the attack.

She went back to court last week with her legal team, claiming the real culprit created multiple Instagram accounts — potentially over 20 of them — to pull off the nasty campaign against Garcelle’s son … and asked the judge for permission to issue the subpoenas to Meta, which is Instagram’s parent company.