Client::

  kex_exchange_identification: read: Connection reset by peer
  Connection reset by 159.195.22.112 port 22

Server::

  $ journalctl -efu ssh
  [...]
  drop connection #10 from [212.99.194.59]:59789 on [159.195.22.112]:22 Maxstartups

``$ man sshd_config``:

 ``MaxStartups``
  Specifies the maximum number of concurrent unauthenticated connections to the SSH daemon. Additional connections will be dropped until  authentication  succeeds or the LoginGraceTime expires for a connection.  The default is 10:30:100.
  Alternatively, random early drop can be enabled by specifying the three colon separated values start:rate:full (e.g. "10:30:60").  sshd(8) will refuse connection attempts  with a probability of rate/100 (30%) if there are currently start (10) unauthenticated connections.  The probability increases linearly and all connection attempts are refused if the number of unauthenticated connections reaches full (60).