Step 1: Disable YUM SSL Verification

Run this single command to tell the package manager to stop checking for valid security certificates:
Bash

echo "sslverify=false" >> /etc/yum.conf

Step 2: Overwrite the Repository Links

Your current repository file is likely still trying to redirect to dead or secure links. We will overwrite it entirely with hardcoded, plain HTTP links to the final CentOS 6 archive.

Copy this entire block of code, paste it into your terminal, and press Enter:
Bash

cat <<EOF > /etc/yum.repos.d/CentOS-Base.repo
[base]
name=CentOS-6.10 - Base
baseurl=http://vault.centos.org/6.10/os/\$basearch/
gpgcheck=0
enabled=1

[updates]
name=CentOS-6.10 - Updates
baseurl=http://vault.centos.org/6.10/updates/\$basearch/
gpgcheck=0
enabled=1

[extras]
name=CentOS-6.10 - Extras
baseurl=http://vault.centos.org/6.10/extras/\$basearch/
gpgcheck=0
enabled=1
EOF

Step 3: Clean and Install

Now that the system is properly wired to the vault via HTTP, clear out the broken cache and run the installation again:
Bash

yum clean all
yum groupinstall "Development Tools" -y
yum install glibc.i686 ncurses-devel zlib-devel perl bc bison flex uboot-tools lzma -y

It should completely bypass the errno 14 SSL block and download the packages normally. Once it finishes, you can proceed straight to the make commands to compile your switch firmware!