What to do if one of the walls of a log house is sagging?

Please advise how you can clean up these walls, the main problem is that one side of the wall is heavily mowed. The house is log and plastered. What materials to use? What would be, as they say, cheap, hard-working and without a lot of hassle. I come up with only two options:

The first is to peel off the shingles with the old plaster, upholster the walls with metal mesh and plaster.

The second is to beat off the old plaster, upholster the house with polystyrene foam, top with moisture-resistant or frost-resistant putty or plaster. (Or maybe it is not necessary to beat off the old plaster at all.)

And another question heard about the hardeners that are added to the plaster, is it worth adding or not.

Maybe do the first crate of timber. Please advise, I'm completely confused.