Stephen *****************
@Luit ****************
The way they've been accepting or rejecting applications, they appear to have internal guidance that is a more narrow requirement than just "remote". It needs to be work that can be done in a "work anywhere" capacity, which is why often people are writing permission letters to themselves to verify that they can work anywhere when they're self-employed. You could, in theory, work remotely from Chiang Mai for a client in London who has a subsidiary or a client themselves in Bangkok and they demand that you be in Thailand to support their client or sub, but that would violate the spirit of the workation category -- assuming anyone would bother to report you to immigration -- and should actually be on a Non-Imm B sponsored by the client or sub rather than a DTV.
I would not want to be the one to test that, but looking at how the workation category quickly became one of the most -- if not THE most -- difficult to get, it's pretty clear they're on the lookout for people trying to avoid Non-Imm B among other things.
I posted my response because of the other replies saying "you are not allowed to work in Thailand" or "you do your freelance work outside of Thailand", neither of which is actually true on the face of it. You do in fact work in Thailand when you're freelancing on a DTV. Indeed, you may become a tax resident doing so if you're in the country long enough; worse yet, no one seems to have really had to test permanent establishment effects yet. The main thing is you can't freelance for a Thai resident organization or person; your clients have to be resident outside of Thailand.