Phragmipedium leaves

[Phragmeister]

It looks to me like two things going on here. You will notice problems with leaves, particularly at the ends, when there is root tip damage and nutrients cannot get to the developing parts of the leaves quick enough to match growth. When in doubt, repot. The other issue that is apparent (from the brown spotting) is likely spider mite damage. You likely won't even see the mites, but the damage is pretty typical. Organic stuff for mites (including oils) is pretty lame. The best solutions are quite toxic and not easily available. If you have access to someone who still has any Wilson's Tree and Shrub spray, that works quite well, though it is no longer for sale. Barring this, you can use 90% alcohol with cotton swabs and wipe off all the leaves every couple of days for about two weeks. Soap spray does not work. Insecticides likewise do not work as mites are not insects. Hope this is of some help. (ps. mites don't like high humidity)

[justatypn]

I have seen this before on plants at work and it appears to me to be a fungus. Typically they begin as yellow areas on the leaves undersides and darken and the spots become visible on both sided. Good air circulation, culture and hygien will help prevent this...spray plants using a fungicide containing benomyl, remove the severe damaged leaves but you can leave the less damaged leaves without doing harm to the rest of the plant.

My first thought was mites as well but they usually start with small patchy yellow spots and this I did not see at least in the photo's shown. If you see small patchy yellow spots it very well may be mites and the alcohol will do the trick.