Update Link Error

No, because this is not a good long-term solution. We should find out why epel doesn’t work. You may try to edit the .repo file, set baseurl and comment metalink, you may also try to change download.fedoraproject.org with another mirror:

https://admin.fedoraproject.org/mirrormanager/mirrors/EPEL/7/x86_64

baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch
#metalink=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch

Can you ping the epel mirror?

You updated to centos 7.5 and are using the new kernel so ndpi module is not working. You may reboot with older kernel and it should work again. For information on the new updates, the problems and solutions see these threads:

You may try:

yum clean all
rm -rf /var/cache/yum