8 Month Old - Stands & Falls

Am struggling with my 8 month old’s sleep. Ever since we put him into his own room 2 months ago we’ve had broken sleep. Up every 90 or so minutes, and between 4-6am refuses to go back into his cot 😴

He’s VERY strong willed. We tried gentle sleep training and he just got more angry with us being in his room. Extinction seems to be the way to go with him.