The systemd service didn't start on ubuntu 20.04

4 systemd service is created to start 4 besu processes on ubuntu 20.04 server under /etc/systemd/system/besu. Here is the node1.service:

cjadmin@ibm-testbox:/etc/systemd/system/besu$ cat node1.service

[Unit]
Description=Besu Enterprise Ethereum java client
After=syslog.target network.target

[Service]
User=myuser
Group=myuser
Environment=HOME=/home/myuser
Type=simple
ExecStart=/bin/sh -c "/home/myuser/bin/besu/bin/besu --config-file=/home/myuser/bin/besu_network/node1/config.toml >> /var/log/besu/node1.log 2>&1"  #<<==start besu service with configuration in  config.toml
SuccessExitStatus=143
Restart=on-failure
RestartSec=10s

[Install]
WantedBy=multi-user.target

The others are node2.service to node4.service. After reboot the server, there is no log files under /var/log/besu/. Then I check the system log by dmesg | less and didn't find any error and didn't see logs for starting besu services as wll. What can be wrong for the systemd services failing to start? Where to see the error?

Update:

$ systemctl status /etc/systemd/system/besu/node1.service
Unit etc-systemd-system-besu-node1.service.mount could not be found.
$ systemctl status node1.service
Unit node1.service could not be found.