The doors have had multiple coast of varnish added over the years and we are trying to stripe them without much success.
What type of paint stripper are you using? With this type of work you might have to use a Methylene chloride-based paint stripper. This is very smelly and dangerous to use (flammable) so please use caution. This is best done outside in good weather and in the shade. Using saw horses is a good idea.
Check out <a href="https://www.house-painting-info.com/paint-stripping.html">Choosing the Right Paint Stripping Technique</a> for more info.
If you can't find this type of paint/varnish stripper in your area you can also sand off most layers then apply your paint stripper to finish the job.