Flatpak not opening some local URLs

[Petrosophia]

On a clean install of the Flatpak, I'm having trouble with local network URLs not working. For example, all of the following URLs point to the same service on my home server.

1. http://photos.ente.home does not work in Zen, but works fine in Firefox and LibreWolf
2. http://bookholm.home:3000 works fine in Zen, Firefox, and LibreWolf
3. http://192.168.88.9:3000 works fine in Zen, Firefox, and LibreWolf

I've tried each of the following individually:

• HTTPS-only mode: disable
• DNS over HTTPS: disable
• Enable DNS over HTTPS using: default protection, off
• No proxy for: 192.168.88.0/24
• Clear DNS cache

Nothing has enabled me to access my home server's web pages using the local URLs I set up. What am I doing wrong?