I guess I’m the only one here who thinks this is related to your water/watering/fertilizer rather than a fungal issue, though the fungal issue could be secondary. What’s your mineral content? What fertilizer are you using? When I’ve seen this brown spotting stuff, it’s been from me using tap water plus fertilizer over a long period. I burnt the roots and the plant started to necrotize, then walk off the necrosis with the brown spot. Just what it looks like to me and I’m far from the most knowledgeable, so please heavily grain-of-salt my thoughts and I in turn defer to others. I’m not saying it can’t also be fungal but the whole plant has a too-much-salt look. Another possibility: Sam uses systemic fertilizer granules in his mixes. Little green balls that wear away over very long periods. If you’re feeding as well, without being conscious of his long-dissolving stuff, it could create a chemical burn. If it’s affecting all your Paphs, as you say, it’s got to be a cultural issue and nothing to do with the vendor. So of course he and we need “cultural specifics like crazy.” People in this forum have solved so many cultural issues for me. One thing nobody here has mentioned is the plant looks dehydrated, which means the roots are not able to do their job. I learned that in here too. Hydration is key. I would unpot every affected plant and clean it, going over every root and leaf surface looking for insect troubles, cutting away what I’m going to guess is a lot of dead root tissue, etc, then I’d soak everybody in their own separate bowl of RO water, completely submerged for several hours, then I’d remove, douse with all the chems, let dry, then pot up into medium soaked in KelpMax (Ray’s got me addicted to the stuff) and keep treating with it until roots form. I’ve been absolutely astonished how that potion can make a rootless plant fill a pot. It’s a godsend if ever there was one. Regarding the spots themselves, nobody has mentioned “Dragon’s Blood,” a plant-based potion I also learned about here, which seems to stop a fungus dead in its tracks when applied directly to the brown area (if this is fungal).
I don’t think I’m contradicting any of the more experienced folks here, just expanding on and throwing out some other ideas. I’m sorry for your troubles. Hoping you’ll share a lot more photos of your whole grow, setup, water/feed details, etc. Hoping for the best outcome for you.