Can I return to Thailand with a non-immigrant O visa after visiting Vietnam for 3 days?

Ruud Maenhout It's a rather small office. From my approach, right past security or the normal immigration check-point (I forget which one). On the normal path to the gates, I took a right turn down a wide hallway and it was on the LHS a short distance. There are only two chairs for customers. When I went in there was only one officer. He was excruciatingly slow in his movements and manner. I cannot imagine how long it would take if there was any kind of line. If possible and convenient for you, I would suggest going to your local immigration office for the stamp. Yes, they can be slow too, but at least you don't have a plane to catch at that moment.