Z.com 的 VPS yum update 出现错误，如何解决？

yum update 时，提示如下：

Loaded plugins: fastestmirror, security
Setting up Update Process
Loading mirror speeds from cached hostfile
epel/metalink                                            | 5.9 kB     00:00     
Could not retrieve mirrorlist http://poptop.sourceforge.net/yum/stable/mirrorlist-poptop-stable-rhel6 error was
14: PYCURL ERROR 56 - "Failure when receiving data from the peer"
Error: Cannot find a valid baseurl for repo: poptop-stable

如何解决？求教！