I recommend Bitvise SSH Server for Windows, which I've used for 10 years. It's free for personal use (also a free trial). As an aside: it supports blocking by

I recommend Bitvise SSH Server for Windows, which I've used for 10 years. It's free for personal use (also a free trial). As an aside: it supports blocking by client identifier, which completely shut down bot connections (and probably will until OpenSSH does the same).