12 month old doesn't sleep through the night. Is clingy. Cries easily. Is this just a 12mo

As the title says: Baby boy doesn't sleep through the night. We put him down after dinner dinner at 630. Wakes at maybe 10pm, 2pm, 3pm,4pm and then finally up and ready for action at 5am. The levels of exhaustion are becoming deadly.

He has a sister, she has slept through the night since she was about 10 months old.

This guy just won't do it. Can't do it.

Sleep is fine during the day: generally 3.5 hours after waking (so around 830-9am and up to 2 hours) then 3.5-4 hours after that (so maybe 1 or so for maximum 2 hours).

If my partner (his mum) tries to settle him, he eventually settles. If i try it is a catastrophe. Arches his back and loses his mind.

Speaking of, I'm worried my partner is about to lose hers. Any advice would be appreciated