Re: seems I have a problem..
Put two baby gates at the end of the hallway, so he can only go as far as you want him to go. (for now)
But, also put high locks on the doors, and cover the stove knobs so he can't get to them. Just make it as kid proof as you can think of so when he's wandering around he can't hurt himself, leave, burn the house down, cook, or destroy something.
I'd also add some bells to anything that opens so you'll hear him.
It's usually a stage that they outgrow, But, I have had two friends who removed the bedroom door and put a security screen door on the bedroom to lock the boys in the bedroom because they were up most of the night FOREVER.
One lady put the son in the master bedroom on the other side of the house, took the knobs off the bathtub so he couldn't turn them on, and put a security door on his bedroom door. He was up most of the night working on the computer, or playing legos, but, if he was allowed freedom of the house, he'd go out in the pool, or out front (they lived in the desert and was the only house for miles..so he could have been killed out there)
They had tried everything else first, and letting him stay awake was the only option they finally decided on.