Need advice for babies nap schedule

My 11 month old has been fighting all his naps for almost 2 weeks now, it usually would take 5 minutes for him to go down for his naps but now it can take up to an hour.

He takes 2 naps a day.

His schedule is as follows: 8:00am wake-up 10:30/11:00 first nap for about an hour 3:30/4:00 second nap for about an hour Bed time is 8:30ish

I find he can be awake for 4-5 hours now and still will fight sleep, I’ve tried to adjust it so his wake windows were shorter just in case he was possibly over tired but it didn’t work.

Should I drop to one nap? Sometimes he doesn’t go to bed until after 9pm because his second nap is so late but he won’t nap any earlier????