Android LAN suddenly won't work anymore

I had this problem before, where packaging for Android and then testing LAN multiplayer with NULL online subsystem resulted in no sessions being found, despite the host device (whether PC or Android) creating a session on the same WiFi network.

It was solved mysteriously in the past by updating my project to v 4.24.3

But now under the same version when I packaged it for shipping and distribution so I can put it in Steam, Google Play, and other stores, it suddenly started failing again.

So I have had to postpone the release of my game far beyond the release date because a problem occurred in the process of getting it into the stores.

In the past, the problem was that the Android devices would always get 127.0.0.1 as their own IP address, and so they couldn’t find each other. The problem one day fixed itself so they reported their actual WiFi router-assigned IP address within that local network.

My game is meant to be played by people within the same local area network, not across the internet.
I cannot find any errors that would say something went wrong.

Is LAN multiplayer this hard to get working for everyone who uses Unreal? Or is it just my project?
I don’t hear about other people having this problem except in the past with older Unreal versions.