FAQ

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1. 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

2. 'colcon build' shows 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.

3. not found

ros2: command not found
Package 'XXX' not found

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

4. General ROS troubleshooting

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

5. Network configuration issues

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

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

# 重新运行不再报错
unitree@ubuntu:~$ sudo ifconfig wlan0 up

6. SSH works but VS Code Remote 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

2. On the Linux server, check network:

unitree@ubuntu:~$ ping marketplace.visualstudio.com

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

3. 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.

4. 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.

5. Restart the DNS service:

unitree@ubuntu:~$ sudo systemctl restart systemd-resolved

6. 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.

7. 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.