FAQ

June 24, 2026 · View on GitHub

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System

Q1. Unable to connect to the network after configuring a custom network

# Remove the default route
sudo ip route del default via 192.168.123.1 dev eth0

Q2. colcon build shows a system clock warning

make[2]: warning:  Clock skew detected.  Your build may be incomplete.

# Check system time
date

If it shows 1970, it may be because the system cannot update the clock automatically due to no network connection.

# Remove default route
sudo ip route del default via 192.168.123.1 dev eth0

Close and reopen the terminal.

# Check time synchronization status
timedatectl status

If the time is updated successfully, delete previous build/install/log files and rebuild:

# Make sure you are in the correct workspace
rm -rf build install log
colcon build

The warning should no longer appear.

Q3. not found

ros2: command not found
Package 'XXX' not found

These issues usually occur when the correct setup files are not sourced.

Q4. For any ROS issue, you can try:

  1. Close all terminals and open a new one.
  2. Delete build, install, and log, then rebuild.

Q5. Network configuration

unitree@ubuntu:~$ sudo ifconfig wlan0 up 
# Error: SIOCSIFFLAGS: Operation not possible due to RF-kill

Solution:

# Check RF-kill status
unitree@ubuntu:~$ rfkill list
# 0: phy0: Wireless LAN
#         Soft blocked: yes
#         Hard blocked: no

unitree@ubuntu:~$ sudo rfkill unblock wifi

# Check again
unitree@ubuntu:~$ rfkill list
# 0: phy0: Wireless LAN
#         Soft blocked: no
#         Hard blocked: no

# Run again; the error should be gone
unitree@ubuntu:~$ sudo ifconfig wlan0 up

Q6. SSH works, but VS Code remote connection fails

Make sure the Download Server has network access and the local network is working.

If VS Code repeatedly asks for a password and shows:

Failed to connect to the remote extension host server (Error: ExtensionInstallFailed(ExtensionInstallFailed("Error while installing extensions: getaddrinfo EAI_AGAIN marketplace.visualstudio.com\ngetaddrinfo EAI_AGAIN marketplace.visualstudio.com\n")

This is a typical network issue where the Linux server cannot access marketplace.visualstudio.com due to DNS failure or timeout.

Solution:

  1. Connect via SSH using Windows PowerShell or Linux terminal:
ssh unitree@192.168.xx.xx
  1. On the Linux server, check network:
unitree@ubuntu:~$ ping marketplace.visualstudio.com

If it fails, the Linux server cannot reach the Internet.

  1. Check DNS configuration:
unitree@ubuntu:~$ cat /etc/resolv.conf

If it shows something like:

nameserver 127.0.0.53 
search Huawei.Local

Ubuntu is using systemd-resolved local DNS stub which cannot resolve external domains.

  1. Edit resolved.conf:
unitree@ubuntu:~$ sudo vim /etc/systemd/resolved.conf

Uncomment or add:

[Resolve] DNS=8.8.8.8 1.1.1.1 
FallbackDNS=114.114.114.114 
DNSStubListener=yes

Save the file.

  1. Restart the DNS service:
unitree@ubuntu:~$ sudo systemctl restart systemd-resolved
  1. Verify DNS:
unitree@ubuntu:~$ systemd-resolve --status

Should show:

DNS Servers: 8.8.8.8 1.1.1.1
Fallback DNS Servers: 114.114.114.114 8.8.8.8

press q to exit.

  1. Test network connectivity:
unitree@ubuntu:~$ ping 8.8.8.8
unitree@ubuntu:~$ ping marketplace.visualstudio.com

If successful, VS Code Remote SSH should now work properly.

Control

Q1. The client cannot discover the robot device

Check these first:

  • Confirm ./launch_robot.sh and ./launch_trans.sh agent have both been started and their outputs look normal.
  • Confirm the robot and the control PC are on the same network.
  • Confirm ports 46000 and 37020 are not already in use.

Q2. Newly added actions do not appear in the UI

Check these first:

  • Confirm the project has been rebuilt.
  • Confirm the current mode is correct in src/control_py/config/smach_config.yaml.
  • Confirm the new action has been added to active.children.
  • Confirm that action ID has not been added to hidden_action_reg.
  • Confirm you restarted the Agent and rescanned the device.

Q3. An action can be triggered, but it cannot switch to the next step

Check these first:

  • Confirm active_expected_duration is not set too long.
  • Confirm allowed_sub_trans is not restricting the next transition.
  • For actions using auto, confirm mark_active_action_done() is called correctly.

Q4. Why does grasping always use the right hand?

In the current code, some grasping entry points and intermediate steps are hard-coded to right. If you want to support the left hand or both hands, you need to update the handling logic in the relevant on_xx_handler functions as well.

Q5. Why does the action not start after an object is recognized?

Common causes:

  • The object is not recognized stably enough. There is currently a stability-check mechanism, so hand motion can cause an object being held to fail the stability check.
  • The detected object bounding box is too close to the edge of the camera view.