I was working with a Pi 1 B and was having issues with cython installing. “Long story here” I was waiting for my new Pi 3 and SD cards. I imaged the first one with the same image I was using on the Pi 1, which I did image several times and each time SSH had no issues.
So my first time to try and image my new micro SD, I could find it in nmap. I could ping it, but I would get some sort of software refused connection message.
So I imaged a 2nd micro SD and it just now worked (as far as SSH).
I still have the 1st SD card if there is any forensic worth trying.