macOS 27 (Golden Gate): app stops connecting to LAN Transmission server, Local Network permission toggle no longer fixes it

On macOS 27 "Golden Gate", TrguiNG (native desktop app) fails to connect to a Transmission RPC server on the local network with "Failed load session". This previously had a reliable workaround (toggling the Local Network permission off/on in System Settings), but that workaround no longer has any effect after upgrading to macOS 27.

• TrguiNG version 1.5.1
• macOS version: 27 "Golden Gate" (clean install, not an upgrade from an older macOS)
• Transmission server 4.0.5: running on a NAS on the same LAN
• Connection URL used: http://192.168.x.x:9092/transmission/rpc/

What used to work (before macOS 27): Opening System Settings → Privacy & Security → Local Network, then toggling the permission for TrguiNG off and back on, would restore the connection.

What happens now (on macOS 27): TrguiNG does appear in the Local Network permission list, and the toggle is present, but toggling it off/on no longer restores connectivity. The app simply never manages to reach the LAN host.

What I've already tried

• Toggling Local Network permission off/on repeatedly — no effect.
• Full reboot of the Mac — no effect.
• Confirmed this is a clean install of macOS 27 (not an in-place upgrade), so there's no stale permission state left over from a previous OS version.
• As a sanity check, port-forwarded the same Transmission RPC port on my router and connected to my public IP instead of the LAN IP (http://<public-ip>:9092/transmission/rpc/) — this works perfectly, which confirms the daemon, the RPC config, and the app's core networking are all fine. The failure is specifically tied to macOS's Local Network privacy mechanism for LAN-range destinations.

Upd. Based on similar reports from other third-party (especially Electron/Qt/Tauri-based) apps after macOS 27 upgraded, Apple appears to have changed how the Local Network permission is enforced — moving from a straightforward TCC-style grant to something tied to Network Extension / the app's code signature. Several other projects (e.g. Moonlight-Qt, Insomnia, Ghostty) have reported the exact same symptom on macOS 27: the app shows up in the permission list, toggling does nothing, and the underlying grant never actually takes effect for that app. This suggests TrguiNG (via Tauri) may need updated handling/entitlements to register correctly with macOS 27's new enforcement.

• Moonlight-Qt: https://github.com/moonlight-stream/moonlight-qt/issues/1910
• Insomnia: https://github.com/Kong/insomnia/issues/9783
• Ghostty: https://github.com/ghostty-org/ghostty/discussions/13482
• LightBurn: https://forum.lightburnsoftware.com/t/macos-27-golden-gate-ethernet-connection-broken-missing-local-network-permission/191601

Start by reproducing the LAN Transmission RPC failure on macOS 27 and compare it with the working public-IP connection. Inspect TrguiNG's Tauri macOS packaging, Local Network permission behavior, and any relevant entitlements or code-signing configuration. Done means a clean macOS 27 installation can connect to the LAN server without relying on the ineffective permission toggle.