404 when using yum

Use yum to upgrade nss today

yum update nss

The result is an error:

http://people.centos.org/tru/devtools-2/6Server/x86_64/RPMS/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404"

Then I went to visit the website http://people.centos.org/tru/devtools-2 and found that the directory structure on the page was a bit different from the above address

The directories here are only 5 and 6, there is no 6Server, and then replace the 6Server in the URL with 6.