initramfs-lts missing from netboot folder in mirrors
http://dl-cdn.alpinelinux.org/alpine/v3.11/releases/x86_64/netboot/ seems to be missing the initramfs files, but they are in the netboot release tarball: http://dl-cdn.alpinelinux.org/alpine/v3.11/releases/x86_64/alpine-netboot-3.11.0-x86_64.tar.gz
The last time they were present was in RC3 if that helps. ( http://dl-cdn.alpinelinux.org/alpine/v3.11/releases/x86_64/netboot-3.11.0_rc3/ )
They are also missing from edge.
Please let me know if you need anymore information.