Right, multicast DNS is mDNS. If DAVx5 supported that, it would enable my use case. In Apple operating systems and most Linux systems, using the standard DNS resolver would be enough to resolve mDNS but for some unfortunate reason (probably business related), Google decided that if an Android app wants to resolve mDNS hostnames, then it needs to use a separate API.
Unfortunately the modem/router provided by my ISP doesn’t have that functionality of registering the client hostname via DHCP. Besides, even if it did I use a separate DNS server (126.96.36.199) for privacy reasons so it wouldn’t work for me.
So mDNS is the only option I can think of (apart from setting up my own local DNS server just for this, which would be more complex and overkill IMHO).
Obviously it’s your call whether to add this functionality to DAVx5 or not, and I don’t mean to insist on it. I just decided to chime in here to point out that it would be useful, and I can’t think of an alternative solution that doesn’t have its own set of downsides.