README and FAQ

Author: Ziwei Chang

FAQ_en.md

@@ -0,0 +1,154 @@
+# FAQ
+
+English Version | [中文版](./FAQ.md)
+
+## 1. Unable to connect to the network after configuring a custom network
+
+```sh
+# 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.
+```
+
+```sh
+# Check system time
+date
+```
+If it shows 1970, it may be because the system cannot update the clock automatically due to no network connection.
+
+```sh
+# Remove default route
+sudo ip route del default via 192.168.123.1 dev eth0
+```
+
+Close and reopen the terminal.
+```sh
+# Check time synchronization status
+timedatectl status
+```
+
+If the time is updated successfully, delete previous build/install/log files and rebuild:
+```sh
+# 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
+```sh
+unitree@ubuntu:~$ sudo ifconfig wlan0 up 
+# Error: SIOCSIFFLAGS: Operation not possible due to RF-kill
+```
+
+Solution:
+```sh
+# 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:
+```sh
+ssh [email protected]
+```
+
+2. On the Linux server, check network:
+```sh
+unitree@ubuntu:~$ ping marketplace.visualstudio.com
+```
+If it fails, the Linux server cannot reach the Internet.
+
+3. Check DNS configuration:
+```sh
+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`:
+```sh
+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:
+```sh
+unitree@ubuntu:~$ sudo systemctl restart systemd-resolved
+```
+
+6. Verify DNS:
+```sh
+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:
+
+```sh
+unitree@ubuntu:~$ ping 8.8.8.8
+unitree@ubuntu:~$ ping marketplace.visualstudio.com
+```
+If successful, VS Code Remote SSH should now work properly.

FAQ.md renamed to FAQ_zh.md

@@ -1,5 +1,6 @@
 # FAQ
 
+[English Version](./FAQ_en.md) | 中文版
 
 ## 1. 配置自定义网络后，可能无法连接网络
 

README.md

@@ -188,4 +188,4 @@ cd ~/unitree-g1-brainco-hand/brainco_ws     # 进入工作空间
 
 
 ## FAQ
-[FAQ.md](./FAQ.md).
+[FAQ 中文](./FAQ_zh.md) or [FAQ English version](./FAQ_en.md)

README_en.md

@@ -193,4 +193,4 @@ Without `l/r`, both hands are controlled.
 
 
 ## FAQ
-[FAQ.md](./FAQ.md).
+[FAQ 中文](./FAQ_zh.md) or [FAQ English version](./FAQ_en.md)