If it cannot be moved
A south-facing door is not the fault the internet makes of it, but the tradition asks for compensation: the door placed in the eastern half of the southern wall, a threshold that is not sunk, and the entrance kept bright rather than shadowed.
What the દક્ષિણ governs
South is Yama’s direction, and it carries weight rather than light. The tradition builds it up — heavy walls, storage, mass — and keeps openings modest.
Where the મુખ્ય દ્વાર belongs
The main door is where the tradition says the house meets the world, and it is the placement most people can still change — a door can be re-hung where a kitchen cannot be moved. The light directions take it; the heavy ones are held to admit what you would rather keep out.