At the moment I have the following connection scheme:
ONU <-> Switch <--> WiFi (wan), PC, NAS
WiFi <-> TV, Phones, etc..
ONU (provider) Public IP 10.10.10.10 (Local DHCP 192.168.1.0/24 — NET1)
WiFi Local IP: 192.168.1.100 in NET1 (Clients DHCP 192.168.31.0/24 — NET2)
PC Local IP: 192.168.1.2
NAS Local IP: 192.168.1.10
TV Local IP: 192.168.31.5
The NAS has DLNA support. But he doesn’t see TV, probably due to the fact that DLNA broadcasts take place on the 192.168.1.0 subnet, which is behind the WAN of the router to which the TV is connected. Any devices can connect directly by IP address to LAN NET1 from NET2.
What settings need to be made in order for DLNA to be available on the TV?
I tried hard to get this to work. I've tried avahi, and smcroute. Others have reported success, but I was never able to. One of the issues is the TTL on the multicast is set to 1, so to have it cross subnets you need to mangle it and I never got that working properly using nftables.
In the end I found rather than trying to fight with DLNA to get it to span multiple subnets, that it was easier to put an instance of minidlna on each subnet. A DLNA server doesn't have to talk to files that are local on that server. If your WiFi is running OpenWrt it should be easy. You could connect to the NAS and mount its files on the WiFi device, and then use minidlna to provide DLNA to clients on both subnets.
It's really weird. However, I did not know much about working with DLNA to understand all the subtleties of his work. A PC located on the same network as the NAS server has and finds DLNA, and connects to it quite successfully. But not WiFi clients. Of course, your suggestion can be used as a workaround or "plugging the hole" solution, but I don't like the whole idea of raising additional instances of the minidlna somewhere else. Is there really no way to put a simple setting to solve this issue? By the way, clients from the 192.168.1.0 network can also connect to clients from the 192.168.31.0 network, so it was strange for me that WiFi clients do not see DLNA.