Sabahttin's place is just next to Galata tower (you can see it from the window). Wi-Fi works great, PCR test & food, coffee shops nearby, 5-minute walk to Sishane Metro station. Lots of fun all day in neighborhood. The only complaint I got is squeaking doors, but given the age of the building, it is reasonable. I strongly suggest Sabahattin's place if you have a group meetup in Istanbul.