Can't connect via ssh, what could be wrong?

Question

SSH

On vmwar'e the virtual server on tsentos turns. When connected to it (immediately after installation) via ssx, successfully.
After some time it won't let you.

ssh [email protected]
[email protected]'s password:
Permission denied, please try again.

It is obvious that the cx config is not touched, everything remains as it was after installing the system, then an interesting case occurs, after 30-50 minutes it allows you to connect again, BUT it already generates a new RSA key and enters using a different key. After a while it won't let me connect again.
What have I already done?
1) Reinstalled the system (did not change the image).
2) Deleted and created a completely new machine in vmwar.

Answer 1

Obviously you have something else at this address. See the match in the arp table.