AnsariSunnah Royal Mosque is located inside  Pinkloa soi 1 its near to the Royal Barge Museum, unfortunately the mosque not no the main road but you need to walk inside an alley ahead of Dusit Temple , its better to get help of locals once your inside the pinkloa soi 1 as paper maps/google map cannot lead you up to the mosque entrance only pedestrian path is the only way , initially once you start walking inside the alley you will feel that your lost as you need to take couple of turns but keep walking asking people around u they are helpful  insha allah you can find it easily
once you reach there, you will be more then happy to see a well maintained  masjid with lot of kids performing there salat , as next to the masjid building there stands a huge thai muslim school i was quite surprised to know that this school also from boarding facilities for students
the time i reached there it was summer vacation and there was on going  summer camp for islamic studies both boys and girls