You could use a custom XferCommand command per PACMAN.CONF(5) with wget using -6
Something like this might work:
XferCommand = /usr/bin/wget -6 -c -O %o %u
tyvm
seems to be working, even with some 404s returned
/var/lib/pacman/sync/multilib.db.part 100%[===================================================================================================================>] 137.53K --.-KB/s in 0.007s
2024-08-14 11:06:10 (19.4 MB/s) - ‘/var/lib/pacman/sync/multilib.db.part’ saved [140827/140827]
--2024-08-14 11:06:10-- https://mirror.osbeck.com/archlinux/multilib/os/x86_64/multilib.db.sig Loaded CA certificate '/etc/ssl/certs/ca-certificates.crt' Resolving mirror.osbeck.com (mirror.osbeck.com)... 2606:4700:20::6819:5e05, 2606:4700:20::ac43:6136, 2606:4700:20::6819:5f05 Connecting to mirror.osbeck.com (mirror.osbeck.com)|2606:4700:20::6819:5e05|:443... connected. HTTP request sent, awaiting response... 404 not found 2024-08-14 11:06:10 ERROR 404: not found.
Does that only happen when it tries to download files ending in .db.sig? If so, I think I read somewhere that db have no sig. So as long as it otherwise works, this error is cosmetic.
Why would you want to do that? pacman attempts to connect via IPv6 first anyway.
autistic fixation with IPV6
This should be the default systemwide.
Is your IPv6 behind NAT (like on a VPN)? See https://wiki.archlinux.org/title/Mullvad#Preferring_IPv6_inside_the_tunnel
The beloved lightweight distro