Less sleep

Wanted to start sleep training. But LO is behaving very differently. He sleeps around 7 hours ( he fuss sometimes in between ) and then he was wide awake. 4 hours up and then he slept for 2.5-3 hours. ( he wakes up in between like his eyes were closed but he was crying , i put him on pacifier )

How can i sleep train him so he can fall asleep straight 10-12 hours.

He dont take naps longer than max 45 minutes. Iam so sleep deprived due to constant waking up between.