The death of popular YouTuber P2istheName is still puzzling investigators ... but we're told cops do not suspect foul play.

Our law enforcement sources provided new details about the circumstances surrounding his death. We're told Philip Enewally, better known by his YouTube name, collapsed on the ground in front of mailboxes at his L.A. apartment building Friday afternoon.

Our sources say the property manager discovered P2istheName and phoned 911, prompting police and paramedics to respond.

We're told paramedics performed life-saving measures on P2istheName, but they ultimately couldn't revive him and he was pronounced dead at the scene.

We're also told there were no immediate signs of drugs or alcohol ... and, as of now, his death is being treated as from natural causes.

Our sources say the L.A. County Coroner has conducted an autopsy and is awaiting toxicology results.

As you may know ... P2istheName rose to prominence after posting NBA 2K and Fortnite gaming videos, before moving to more general video game content. He posted lots of "Let's Plays" -- walk-throughs of popular video games -- and went on to start his own clothing line, WallyCo.

P2istheName was 26.