Removing a layer of wallpaper with plaster on top?

[Nanako]

The wall behind my toilet appears to be either plasterboard, or wood with plaster over it. That is the main part of the wall, which was revealed in a few areas. This is what i want to strip it back to, its thick and sturdy

But over the top of THAT is some kind of layer of brown wallpaper, and then an extra layer of thin white plaster, which makes me shudder to touch, its the tactile equivilant of nails on a chalkboard. I'm not 100% sure that it IS plaster, but its too dry, soft and powdery to be paint. Yet the paper is giving it integrity
and then a layer of paint on top of it
thankfully the paint is dried out and flaking off easily, ive been at it with a scraper all day. But the paper and plaster are holding much firmer, ive tried a steam cleaner and the results are not good, it will not come off without a fight. At least, the paper layer won't, its stuck much harder than wallpaper usually is. The white layer turns to paste under steam, but wiping it off bit by bit would be very slow going. The problem is really the bond between paper and underlying plaster

I've attached some pictures of what i'm dealing with, you can see
-Base plaster (pinkish brown)
-Paper (brown and ragged)
-Second layer of plaster (white)
-Flaky outer paint (green)

I want the last three layers gone, so that i can patch and paint the base plaster

any thoughts as to how? or info on what i'm dealing with here

 

[Wayners]

I think that's plasterboard.
The paper that has come off the plasterboard. It shouldn't do that.
The damp or time has caused paper delamination.

The filler could be a ready-mixed that was used to make good the damage then lining paper over.

SBR and plaster skim with plastering mesh over entire wall

 

[Nanako]

I think that's plasterboard.
The paper that has come off the plasterboard. It shouldn't do that.
The damp or time has caused paper delamination.

The filler could be a ready-mixed that was used to make good the damage then lining paper over.

SBR and plaster skim with plastering mesh over entire wall

some of it has come off from my scraping

but some of it also had come off over time due to the damp yes
i would have left it in place otherwise, but since it had started coming off i figured i should get rid of it all

unfortunately this is proving VERY DIFFICULT, the damn paper doesnt want to come off, i request advice on how to accomplish this