It took me a while to figure out why many of my self-hosted services were intermittently failing to connect on my phone after updating to Android 17. I eventually figured out there's a new ACCESS_LOCAL_NETWORK permission which means the "Nearby devices" permission is now required to access devices on the same network subnet. For an avid self-hoster, this can be quite a bit.
I had my DNS configured so my public-facing server resolved to a local IP address when on my LAN. This meant that my web, immich, xmpp, NTP, jellyfin and DoH servers all resolved to a local IP address on wifi. On Android 17, it all broke without warning. No error messages. No asking for extra permissions. Just silent packet dropping.
I've solved it by configuring my public-facing services to resolve to my external (static) IP address, even when inside the network. I couldn't make any internal services resolve to the external address (SMB, CUPS etc) because they are (obviously) not bound to my WAN interface.
I get why the change was made. A lot of apps were snooping around people's networks to gather intel. A potentially massive privacy violation.
Has anyone else had this issue? Is this the cleanest solution?
I'm in the same boat as well, for some reason my music apps can't seem to see my Google smart speakers, but strangely they can see my Nvidia shield and cast to that.
Looked through my app permissions I honestly can't see anything out of the ordinary or plainly obvious. Both my speakers and android TV (shield) are on separate segment VLAN.
As for granting the permission, I generally like to grant on a app by app basis, lots of apps ask for internet access as a example but don't actually require it to function. All my game apps for example are completely offline.