Toilets, Sinks, Showers, Tubs and Disposals - External tub stopper

The tub in my in-laws house will not drain. It's an unusual setup I've never seen before and don't understand. The stopper for the tub is external to the tub. To activate it you twist a knob on the top of a 12 high chrome pipe, which then goes down into the pipe to stop the water. The drain pipe from the tub goes directly to the pipe, and that's where I'm confused. When I try snaking from the pipe the snake will only go to the bottom of the pipe. If I snake from the tub drain the snake comes out the external pipe. Where does the water go out? And how do I clear this thing?

I would try a commercial drain opener first. If it's a first floor bathroom, can you see the pipes in the cellar?

Already tried a commercial drain opener. Didn't do a thing. And unfortunately it is a 2nd floor bathroom. No access to the pipes without opening up the floor or the ceiling below.

Opening the ceiling might be the next step.

Edit: I just thought of something. What does is take to disassemble the external stopper from inside the bathroom?

The top unscrews, and the plunger mechanism comes out. Thats how I get the snake into the pipe. But thats as far as it goes. I'd have to rip up the floor to go any further.

What's easier, opening the floor or the ceiling below? Would a vet vac help if you went through the floor?

Opening the floor would be easier. I'd like to avoid it if possible. Vet Vac?

If yoy can get the hose of a water vacuum down the pipe, you maybe able to suck out what's blocking it.

I like that idea. I'm going down there Friday, I'll let you know what happens.