U0040  filed a orphan request for udptunnel :
The URL for the download 404s and has done so since at least 2017. There is a new URL available but the maintainer seems inactive and has not responded to my email.
 https://aur.archlinux.org/account/U0040/  https://aur.archlinux.org/pkgbase/udptunnel/
Request #14478 has been accepted by polyzen .