Cafè De Thaan Aoan
This family owned Cafe is located in the middle of Old Town, which is convenient if you’re planning some temple hopping in-between work. The interior is simple, old style and has more of a restaurant feeling then a cafe. The food is also more restaurant type, offering a wide choice of tasty Thai dishes.
There is an outside seating area that, due to its location at the crossing between two of the major streets in Old Town, can be too noisy and polluted to be able to work from for long hours. The inside is quiet enough and has soft background music. It also offers a few seating options; low sofas and taller, more appropriate, tables.
The internet is free and pretty fast. They have two access points, both with the same speed, and when I was there one of them stopped working but I just needed to switch and it was fine.