Hyper-V guest hostname doesn't resolve in local network

archlinux needs samba to broadcast a hostname using the netbios protocol that Windows clients use.

Install and configure samba in the guest:

pacman -Sy samba
nano /etc/samba/smb.conf

put

workgroup = WORKGROUP
netbios name = Hyper-al

WORKGROUP is the default and sufficient if the guest doesn't need to join a WG.

Enable the services:

systemctl enable smbd.service
systemctl enable nmbd.service

Reboot.