Download of appfeed failed.
Community Applications requires your server to have internet access. The most common cause of this failure is a failure to resolve DNS addresses. You can try and reset your modem and router to fix this issue, or set static DNS addresses (Settings - Network Settings) of 208.67.222.222 and 208.67.220.220 and try again.

要梯子

多试几次

搜索 52help 网站上的 apps安装不上的解决办法，按步骤操作正常都能连上
另保证电脑 日期时间 准确。

多试几次，改改dns试试

通过修改hosts可以临时解决这个问题，在命令行模式下输入vi /etc/hosts，在hosts文件中添加以下内容保存就可以继续了。
199.232.4.133 raw.githubusercontent.com
来自https://www.52help.net/unraid/270.html

这是安装失败的提示...
这是修改后的hosts文件...按照上面52help网站给的教程改的，但还是没有用...

修改hosts后，还是打不开CA市场。

Community Applications requires your server to have internet access. The most common cause of this failure is a failure to resolve DNS addresses. You can try and reset your modem and router to fix this issue, or set static DNS addresses (Settings - Network Settings) of 208.67.222.222 and 208.67.220.220 and try again.
按照提示，把你的unraid的DNS改成208.67.222.222 、208.67.220.220试试，或者安装地址用这个 https://www.52help.net/ad/nas/Squidly271/community.applications/master/plugins/community.applications.plg

先自己 Ping 下 raw.githubusercontent.com
用得到raw.githubusercontent.com对应的IP
打开U盘config目录下的go文件，加入一行：
echo "185.199.110.133 raw.githubusercontent.com" >> /etc/hosts
上面的185.199.110.133用你得到的IP代替
改好后保存，插U盘到机器，再试吧
CA还是用：https://raw.githubusercontent.com/Squidly271/community.applications/master/plugins/community.applications.plg

要科学的。