Appointment not required but highly recommended. My last extension application I was in and out in 45mins. I jumped the queue and was attended to very promptly
Some people might find it useful to know that there's no such thing as an ASEAN passport, or a European passport, especially where Thai immigration is concerned
I know what ASEAN is. What you probably don't realise is Thailand immigration looks at every passport country independently, same as Europe. Thailand immigration deals with COUNTRIES not with trading or political blocs, or continents. You have a lot to learn, maybe you should be googling!! 😂😂😂
Which means absolutely nothing in the context of obtaining a visa for Thailand. Perhaps if you gave proper information when asking for advice you would get much better advice