systemdサービスがユーザーのホームディレクトリにアクセスできないため、サービスを再起動した後に機能するのはなぜですか？

SSHを使用して中央サーバーにコールバックするシステムサービスを作成しました。

[Unit]
Description=Create a tunnel in the cloud back to SSH on this machine
After=network-online.target

[Service]
User=mindhive
ExecStart=/usr/bin/ssh -o ServerAliveInterval=20 -o ServerAliveCountMax=3 -o ExitOnForwardFailure=yes -o StrictHostKeyChecking=no -i /home/mindhive/.ssh/tunnel.id_rsa -N -T -R1822:localhost:22 tunnel@***server-hidden***
RestartSec=60
Restart=always

[Install]
WantedBy=multi-user.target

私はこれを多くのサーバーで使用していますが、すべてUbuntu 16.04です。突然彼らの一人が仕事を止めました。.sshhomedirへのアクセスに関連しているというログ（下）を見ることができます。サービスが確立されたため、Restart=always再RestartSec=60起動後1分ごとに再試行しますが、毎回失敗します。しかし、sudo systemctl restart ssh-tunnel.service手動で起動しても問題ありません。

以下のログ（出力）でjournalctl失敗して再試行するのがわかりますが、手動で起動すると14:54:10に正常に起動します。

今までグーグルとサービスの両方をWorkingDirectory=~追加してみました。ProtectHome=offしかし、それには違いはありません。

sshsystemdを再起動してから起動すると、ユーザーのhomedirにアクセスできなくなりますが、手動で起動するとアクセスできるのはなぜですかsystemctl？

-- Reboot --
Feb 24 14:50:12 ***servername*** systemd[1]: Started Create a tunnel in the cloud back to SSH on this machine.
Feb 24 14:50:12 ***servername*** ssh[1252]: Warning: Identity file /home/mindhive/.ssh/tunnel.id_rsa not accessible: No such file or directory.
Feb 24 14:50:13 ***servername*** ssh[1252]: Could not create directory '/home/mindhive/.ssh'.
Feb 24 14:50:14 ***servername*** ssh[1252]: Failed to add the host to the list of known hosts (/home/mindhive/.ssh/known_hosts).
Feb 24 14:50:15 ***servername*** systemd[1]: ssh-tunnel.service: Main process exited, code=exited, status=255/n/a
Feb 24 14:50:15 ***servername*** systemd[1]: ssh-tunnel.service: Unit entered failed state.
Feb 24 14:50:15 ***servername*** systemd[1]: ssh-tunnel.service: Failed with result 'exit-code'.
Feb 24 14:51:15 ***servername*** systemd[1]: ssh-tunnel.service: Service hold-off time over, scheduling restart.
Feb 24 14:51:15 ***servername*** systemd[1]: Stopped Create a tunnel in the cloud back to SSH on this machine.
Feb 24 14:51:15 ***servername*** systemd[1]: Started Create a tunnel in the cloud back to SSH on this machine.
Feb 24 14:51:15 ***servername*** ssh[1367]: Warning: Identity file /home/mindhive/.ssh/tunnel.id_rsa not accessible: No such file or directory.
Feb 24 14:51:16 ***servername*** ssh[1367]: Could not create directory '/home/mindhive/.ssh'.
Feb 24 14:51:17 ***servername*** ssh[1367]: Failed to add the host to the list of known hosts (/home/mindhive/.ssh/known_hosts).
Feb 24 14:51:18 ***servername*** systemd[1]: ssh-tunnel.service: Main process exited, code=exited, status=255/n/a
Feb 24 14:51:18 ***servername*** systemd[1]: ssh-tunnel.service: Unit entered failed state.
Feb 24 14:51:18 ***servername*** systemd[1]: ssh-tunnel.service: Failed with result 'exit-code'.
Feb 24 14:52:18 ***servername*** systemd[1]: ssh-tunnel.service: Service hold-off time over, scheduling restart.
Feb 24 14:52:18 ***servername*** systemd[1]: Stopped Create a tunnel in the cloud back to SSH on this machine.
Feb 24 14:52:18 ***servername*** systemd[1]: Started Create a tunnel in the cloud back to SSH on this machine.
Feb 24 14:52:18 ***servername*** ssh[1370]: Warning: Identity file /home/mindhive/.ssh/tunnel.id_rsa not accessible: No such file or directory.
Feb 24 14:52:19 ***servername*** ssh[1370]: Could not create directory '/home/mindhive/.ssh'.
Feb 24 14:52:20 ***servername*** ssh[1370]: Failed to add the host to the list of known hosts (/home/mindhive/.ssh/known_hosts).
Feb 24 14:52:20 ***servername*** systemd[1]: ssh-tunnel.service: Main process exited, code=exited, status=255/n/a
Feb 24 14:52:20 ***servername*** systemd[1]: ssh-tunnel.service: Unit entered failed state.
Feb 24 14:52:20 ***servername*** systemd[1]: ssh-tunnel.service: Failed with result 'exit-code'.
Feb 24 14:53:21 ***servername*** systemd[1]: ssh-tunnel.service: Service hold-off time over, scheduling restart.
Feb 24 14:53:21 ***servername*** systemd[1]: Stopped Create a tunnel in the cloud back to SSH on this machine.
Feb 24 14:53:21 ***servername*** systemd[1]: Started Create a tunnel in the cloud back to SSH on this machine.
Feb 24 14:53:21 ***servername*** ssh[1393]: Warning: Identity file /home/mindhive/.ssh/tunnel.id_rsa not accessible: No such file or directory.
Feb 24 14:53:21 ***servername*** ssh[1393]: Could not create directory '/home/mindhive/.ssh'.
Feb 24 14:53:22 ***servername*** ssh[1393]: Failed to add the host to the list of known hosts (/home/mindhive/.ssh/known_hosts).
Feb 24 14:53:23 ***servername*** systemd[1]: ssh-tunnel.service: Main process exited, code=exited, status=255/n/a
Feb 24 14:53:23 ***servername*** systemd[1]: ssh-tunnel.service: Unit entered failed state.
Feb 24 14:53:23 ***servername*** systemd[1]: ssh-tunnel.service: Failed with result 'exit-code'.
Feb 24 14:54:10 ***servername*** systemd[1]: Stopped Create a tunnel in the cloud back to SSH on this machine.
Feb 24 14:54:10 ***servername*** systemd[1]: Started Create a tunnel in the cloud back to SSH on this machine.