(2017-12-06)
Problem
Kitty/Putty barfs with:
Disconnected: Server protocol violation: unexepcted SSH2_MSG_UNIMPLEMENTED packet
Solution
Under Connection -> SSH -> Kex, move
Diffe-Hellman group 14 above
Diffie-Hellman group exchange
Comment
I save all this stuff as Default Settings so they get loaded as the default settings.