wsl2+ubuntu20安装ros2遇到update问题

问题描述

安装ROS2的时候发现的问题
按照官方文档去update的时候发现报错

$ sudo apt-get update
Hit:1 https://mirrors.ustc.edu.cn/ubuntu focal InRelease
Hit:2 https://mirrors.ustc.edu.cn/ubuntu focal-updates InRelease
Hit:3 https://mirrors.ustc.edu.cn/ubuntu focal-backports InRelease
Hit:4 https://mirrors.ustc.edu.cn/ubuntu focal-security InRelease
Hit:5 https://mirrors.ustc.edu.cn/ubuntu focal-proposed InRelease
Get:6 http://packages.ros.org/ros2/ubuntu focal InRelease [4685 B]
Get:7 http://192.168.111.241:8081/IXCab54c6e78e30452664e287da766c009c_10.21.201.233/ros2/ubuntu focal/main amd64 Packages [1133 kB]
Err:7 http://192.168.111.241:8081/IXCab54c6e78e30452664e287da766c009c_10.21.201.233/ros2/ubuntu focal/main amd64 Packages
  File has unexpected size (1042131 != 1132813). Mirror sync in progress? [IP: 192.168.111.241 8081]
  Hashes of expected file:
   - Filesize:1132813 [weak]
   - SHA256:3a16ee61cd5f0a7b4e819a01721cf70a6b4cc15224083313e66f06a90dbd7589
   - SHA1:bce08ea944bac9b639997f30f31b71fdeec32a3e [weak]
   - MD5Sum:511600d9e5e19731670c95d59e265632 [weak]
  Release file created at: Mon, 29 Aug 2022 15:18:43 +0000
Fetched 4685 B in 1s (4636 B/s)
Reading package lists... Done
E: Failed to fetch http://192.168.111.241:8081/IXCab54c6e78e30452664e287da766c009c_10.21.201.233/ros2/ubuntu/dists/focal/main/binary-amd64/Packages.gz  File has unexpected size (1042131 != 1132813). Mirror sync in progress? [IP: 192.168.111.241 8081]
   Hashes of expected file:
    - Filesize:1132813 [weak]
    - SHA256:3a16ee61cd5f0a7b4e819a01721cf70a6b4cc15224083313e66f06a90dbd7589
    - SHA1:bce08ea944bac9b639997f30f31b71fdeec32a3e [weak]
    - MD5Sum:511600d9e5e19731670c95d59e265632 [weak]
   Release file created at: Mon, 29 Aug 2022 15:18:43 +0000

先大概看一下报错信息，我明明修改软件源为

http://packages.ros.org/ros2/ubuntu

但是update的时候却解析成了

http://192.168.111.241

感觉可能是DNS的问题（？）

解决方法

1. 关掉代理服务器
2. 检查是否用了校园网，如果用了校园网需要更换为手机热点（或其他网络）