SSHFS mysteries

Problem:
'read: Connection reset by peer'
..when trying to establish an sshfs mount.

The solution becomes obvious when you try to manually connect with ssh:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!

the fingerprint sent from the host is different from the stored one. In my case due to an reinstallation on the host. In your case probably due to an Man-in-the-middle attach.

So go check the fingerprint of the public key on the host with the ssh-keygen -l -f YOUR_KEY_FILE command, delete the wrong entry from your known_hosts file and reconnect with ssh, then compare the fringerprint sent by the host with the one on the host and accept it.