Disable IPv6 on RHEL/ALMA/ROCKY

There are two methods to achieve this, the first is quite brutal but effective and the second is more forgiving - but sysctl may well be depreciated in future kernels. 

Method 1:

Add the following to the end of GRUB_CMDLINE_LINUX in /boot/grub/grub.cfg

ipv6.disable=1

(on EFI systems you also need /boot/efi/EFI/almalinux/grub2.cfg - replace with your flavour)

Then reboot.

Method 2:

Add the following lines to /etc/sysctl.conf

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

Then run

sysctl -p

and reboot.