When poxa run as a service in Ubuntu 16.4 an error is occur

[codecube47]

SERVICE

[Unit]
Description="poxa"
After=network.target
After=systemd-user-sessions.service
After=network-online.target

[Service]
User=root
Type=forking
ExecStart=/root/poxa/_build/prod/rel/poxa/bin/poxa start
ExecStop=/root/poxa-stop.sh
TimeoutSec=30
Restart=on-failure
RestartSec=30
StartLimitInterval=350
StartLimitBurst=10

[Install]

ERROR

Feb 08 08:22:44 poxa-server sshd[2845]: Failed password for root from 221.194.47.233 port 39569 ssh2
Feb 08 08:22:44 poxa-server sshd[2847]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=58.218.198.165  user=root
Feb 08 08:22:45 poxa-server sshd[2843]: Failed password for root from 221.194.47.245 port 35655 ssh2
Feb 08 08:22:45 poxa-server sshd[2843]: Received disconnect from 221.194.47.245 port 35655:11:  [preauth]
Feb 08 08:22:45 poxa-server sshd[2843]: Disconnected from 221.194.47.245 port 35655 [preauth]
Feb 08 08:22:45 poxa-server sshd[2843]: PAM 2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=221.194.47.245  user=root

LOCAL COMMAN (Successfully works)

/root/poxa/_build/prod/rel/poxa/bin/poxa start

[codecube47]

I changed my server to ubuntu 18.0, install elixir using "asdf" and change configuration as blew, now is working fine

[Unit]
Description="poxa"
After=network.target
After=systemd-user-sessions.service
After=network-online.target

[Service]
User=root
Type=forking
ExecStart=/root/poxa/_build/prod/rel/poxa/bin/poxa start
ExecStop=/root/poxa/_build/prod/rel/poxa/bin/poxa stop
TimeoutSec=30
Restart=on-failure
RestartSec=30
StartLimitInterval=350
StartLimitBurst=10

[Install]
WantedBy=multi-user.target