Automatically Rebooting a MeshCore Room Server Connected to Ubuntu 26.04

Automatically Rebooting a MeshCore Room Server Connected to Ubuntu 26.04

I recently ran into an issue where my MeshCore observer node was showing as offline or potentially offline in MeshCore Analyzer, even though the Room Server hardware appeared to be running normally.

In my case, the setup was a Heltec WiFi LoRa 32 V4 running as a
MeshCore Room Server, connected over USB to an Ubuntu 26.04 Server Minimal system. The serial device appeared as:

/dev/ttyACM0

After manually rebooting the Heltec Room Server, the observer came back online. That made the fix pretty simple: schedule Ubuntu to reboot the Room Server automatically once per day.

The Important Discovery

The MeshCore Room Server does not behave like a normal serial companion node. It needs to be accessed in repeater mode using the -r option.

This command did not work:

meshcore-cli -s /dev/ttyACM0 reboot

It returned an error similar to:

No response from meshcore node, disconnecting
Are you sure your node is a serial companion?
To connect to a repeater, use -r option.

The working command was:

meshcore-cli -r -s /dev/ttyACM0 reboot

Step 1: Confirm Ubuntu Sees the Device

ls -l /dev/ttyACM0

You can also use MeshCore CLI’s device selector:

meshcore-cli -S

My device showed up as:

/dev/ttyACM0
heltec_wifi_lora_32 v4 - TinyUSB CDC

Step 2: Test the Reboot Command Manually

Before automating anything, test the command manually:

meshcore-cli -r -s /dev/ttyACM0 reboot

If successful, MeshCore CLI will connect to the Room Server, issue the reboot
command, and then disconnect as the device restarts.

Step 3: Find the Full Path to meshcore-cli

Cron uses a limited environment, so use the full path to the command.

which meshcore-cli

On my system, it returned:

/root/.local/bin/meshcore-cli

Step 4: Install Cron if Needed

Because this was an Ubuntu 26.04 Server Minimal install, cron was not installed by default.

sudo apt update
sudo apt install cron

Enable and start cron:

sudo systemctl enable --now cron

Verify it is running:

systemctl status cron

Step 5: Check the Server Time Zone

My Ubuntu server was running in UTC. Since cron follows the system time zone, I changed the server to Eastern Time.

timedatectl

sudo timedatectl set-timezone America/New_York

Verify the change:

timedatectl

Step 6: Create the Daily Reboot Cron Job

Edit root’s crontab:

sudo crontab -e

Add the following line:

0 2 * * * /root/.local/bin/meshcore-cli -r -s /dev/ttyACM0 reboot >> /var/log/meshcore-reboot.log 2>&1

This runs the reboot command every day at 2:00 AM and writes
output to:

/var/log/meshcore-reboot.log

Step 7: Verify the Cron Job

sudo crontab -l

To monitor the reboot log:

tail -f /var/log/meshcore-reboot.log

To monitor cron activity:

sudo journalctl -u cron -f

Optional: Test the Cron Job

To avoid waiting until 2:00 AM, temporarily schedule the job a few minutes in
the future. For example, if the current time is 13:46, set it for 13:48:

48 13 * * * /root/.local/bin/meshcore-cli -r -s /dev/ttyACM0 reboot >> /var/log/meshcore-reboot.log 2>&1

Once confirmed, change the cron job back to the daily 2:00 AM schedule:

0 2 * * * /root/.local/bin/meshcore-cli -r -s /dev/ttyACM0 reboot >> /var/log/meshcore-reboot.log 2>&1

Final Working Command

/root/.local/bin/meshcore-cli -r -s /dev/ttyACM0 reboot

Final Cron Entry

0 2 * * * /root/.local/bin/meshcore-cli -r -s /dev/ttyACM0 reboot >> /var/log/meshcore-reboot.log 2>&1

Conclusion

If your MeshCore Room Server is connected to Ubuntu over USB and your observer node is showing as offline or potentially offline in MeshCore Analyzer, rebooting the Room Server may bring it back online.

The key is remembering that the Room Server must be accessed as a repeater:

meshcore-cli -r -s /dev/ttyACM0

This is not a replacement for troubleshooting firmware, MQTT, broker, network, or observer issues, but for a small unattended deployment, a scheduled early-morning reboot is a practical reliability improvement.