Bug#968994: openssh-server: sshd disconnect the connection attempts sometimes

Package: openssh-server
Version: 1:7.9p1-10+deb10u2
Severity: normal

Dear Maintainer,

*** Reporter, please consider answering these questions, where appropriate ***

Sometime I should try to connect to my sshd server several times
before generic login prompt is appeared.
I am using RSA public key on my ssh client PC.
This bug is appeared oftenly on Debian 10 buster.
I am sorry, I can't say more about it, because this disconnects or resets are
unpredictable (unexpectedly) for me.

   * What led up to the situation?
   * What exactly did you do (or not do) that was effective (or
     ineffective)?
   * What was the outcome of this action?
   * What outcome did you expect instead?

*** End of the template - remove these template lines ***


-- System Information:
Debian Release: 10.5
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.19.0-10-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages openssh-server depends on:
ii  adduser                3.118
ii  debconf [debconf-2.0]  1.5.71
ii  dpkg                   1.19.7
ii  libaudit1              1:2.8.4-3
ii  libc6                  2.28-10
ii  libcom-err2            1.44.5-1+deb10u3
ii  libgssapi-krb5-2       1.17-3
ii  libkrb5-3              1.17-3
ii  libpam-modules         1.3.1-5
ii  libpam-runtime         1.3.1-5
ii  libpam0g               1.3.1-5
ii  libselinux1            2.8-1+b1
ii  libssl1.1              1.1.1d-0+deb10u3
ii  libsystemd0            241-7~deb10u4
ii  libwrap0               7.6.q-28
ii  lsb-base               10.2019051400
ii  openssh-client         1:7.9p1-10+deb10u2
ii  openssh-sftp-server    1:7.9p1-10+deb10u2
ii  procps                 2:3.3.15-2
ii  ucf                    3.0038+nmu1
ii  zlib1g                 1:1.2.11.dfsg-1

Versions of packages openssh-server recommends:
ii  libpam-systemd [logind]  241-7~deb10u4
ii  ncurses-term             6.1+20181013-2+deb10u2
ii  xauth                    1:1.0.10-1

Versions of packages openssh-server suggests:
pn  molly-guard   <none>
pn  monkeysphere  <none>
pn  rssh          <none>
pn  ssh-askpass   <none>
pn  ufw           <none>

-- debconf information:
* openssh-server/permit-root-login: false
  openssh-server/password-authentication: true
  ssh/disable_cr_auth: false
  ssh/encrypted_host_key_but_no_keygen:
* ssh/use_old_init_script: true
  ssh/vulnerable_host_keys: