How do you get a 6mo to nap

I’m at my wits end. My 6mo takes hour and half to fall asleep and sometimes skips naps altogether after we’ve tried everything for 2.5 hrs. I try rocking her, lying next to her, white noise everything. She used to be sooo easy I would lie her down and she was asleep in 5min. This past week she will not nap then wants to go to bed at 4-5 pm which means she’s up at 2am ready for the day.

She takes two 30min naps and that’s it