You didn't come out and say so, but it sounds to me like you are appearing and representing yourself pro se. I'm attaching an article below that seems to indicate that the motion you made is very difficult and that the conflicts of interest must be clear and compelling and not a mere technical "gotcha" that an attorney happened to represent one of the parties before.
The article mentions a "clear and compelling" burden of proof, which is a high burden. This is likely what the Judge probably had in mind by calling your motion "legally insufficient".
The article seems to suggest this burden of proof is high and a failed effort to make this motion may damage your credibility more than making the motion is worth, given the low probability of success.
I'm not sure what the Court meant by wrong forum, and am not a Florida attorney, so he many have meant this motion should have been made in a different court or before a different judge (e.g. superior court judge vs. family court judge vs. support magistrate vs. appellate court or state bar ethics committee, etc., it's hard to say, perhaps a FL attorney can make a better guess than me on this point.
The article below, however, suggests that this kind of motion is far from straightforward and should only be attempted, if at all, by a skilled litigation attorney and not by a pro se litigant. Would you do surgery on a family member after reading an article about a disease on Web M.D. It's kind of like that, or "closed course - professional driver" or "don't try this trick at home" warnings.
I'm licensed in California although I tend to agree. If you're representing yourself, you might not have presented the salient facts to the judge in a manner that the judge could rule in your favor. Great advice by learned counsel on this forum. A consultation with a family law lawyer licensed in your state ought to answer your questions. If you want to file a motion for reconsideration or similar motion, you do have certain timelines in hich to file per Florida statutes and local rules. I wouldn't dawdle and would call a Florida lawyer who can advise you.
Ms. Johns can be reached at either her Woodland Hills or San Diego offices at (866) 402-4038. Her email address is email@example.com. Ms. Johns is a lawyer although she is not your lawyer unless and until you have consulted with her and an authorized representative of her office and signed a fee or letter agreement confirming her representation of you. Ms. Johns, their lawyers, and her employees are not tax or financial advisors and do not give tax or financial advice. If you wish such professional advice, you are advised to consult with the appropriate professionals.