I use Tailscale on Android 13 devices; there is a subnet router in my Tailnet which advertises a single IPv6 route to my home network. This works fine under ‘normal’ conditions.
However, when my Android device is connected to an IPv4-only WiFi network (which means the cellular data network is not active), it is unable to resolve DNS hostnames for my home serviers, because they are only reachable via IPv6 and there are only AAAA records in DNS for them. If I try to access one of these servers directly by its address it works fine. I do not use ‘Tailscale DNS’, I only use the DNS resolvers provided by the WiFi network I’m connected to.
As best I can tell from my testing, the Android DNS client won’t issue queries for AAAA records unless there is at least one GUA (not just ULA) present on the device. When I connect to a WiFi network which provides an IPv6 GUA, then DNS resolution of these hostnames works fine.
Ideally, I’d prefer if my Tailnet used GUAs instead of ULAs; it would resolve this problem, and I don’t think that using ULAs is providing any benefit here. Is there any way to use GUAs in Tailscale?