我之前已经设置了多个服务器，没有任何问题，但是运行之后apt-get 更新经过长时间的等待后，我看到了这一点：
Err http://apt.rackster-server.ch wheezy/updates/contrib amd64 Packages
Unable to connect to apt.rackster-server.ch:http:
W: Failed to fetch http://apt.rackster-server.ch/debian/packages/dists/wheezy/Release.gpg Could not connect to apt.rackster-server.ch:80 (213.133.99.97). - connect (110: Connection timed out)
运行 Debian Wheezy x64。因此无法安装 Java。我该怎么做才能排除故障或找到问题？