Err:1 http://syssw.localdomain.com buster InRelease
      The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 89EE0AACFE87EF86
    Reading package lists... Done
    W: GPG error: http://syssw.localdomain.com buster InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 89EE0AACFE87EF86
    E: The repository 'http://syssw.localdomain.com buster InRelease' is not signed.
    N: Updating from such a repository can't be done securely, and is therefore disabled by default.
    N: See apt-secure(8) manpage for repository creation and user configuration details.