I have painted two doors with Dulux Exterior Gloss and the finish is
terrible. Loads of little specks of undercoat showing through in a sort
of
orange peel effect.

Can you post pictures?

Also, it might be an idea to state the exact preparation and sequence you
went through. Was it new wood, old wood, previously coated? Was it sanded or
planed? What types of primers, undercoats and gloss were used? Acrylic or
alkyd/solvent? Was it raining? What was the temperature? What species of
wood? Did you rub down between coats? etc.

Christian.