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The Fluxer desktop client installed via Flatpak opens with a blank/gray window and does not load the web interface. When started from a terminal, Electron repeatedly fails to load https://web.fluxer.app/ with: DNS resolution itself works both on the host and from inside the Flatpak sandbox, and web.fluxer.app is reachable over both IPv4 and IPv6. Disabling Chromium/Electron's AsyncDns feature makes Fluxer load normally: Manually mapping the hostname with --host-resolver-rules also makes the client load immediately. Expected behaviour: Fluxer should resolve web.fluxer.app and start normally without requiring additional Chromium command-line flags.

1. Install the current stable Fluxer desktop client from Flathub (app.fluxer.Fluxer).

2. Start Fluxer normally:

~bash flatpak run app.fluxer.Fluxer ~

3. A blank/gray Fluxer window opens and the application does not load.

4. The terminal log repeatedly reports:

~text ERR_NAME_NOT_RESOLVED https://web.fluxer.app/ ~

5. Verify that DNS resolution works on the host:

~bash getent ahostsv4 web.fluxer.app getent ahostsv6 web.fluxer.app ~ Results: ~text 45.63.21.197 STREAM web.fluxer.app 2001:19f0:4000:174e::1 STREAM web.fluxer.app ~

6. Verify that DNS also works inside the Fluxer Flatpak sandbox:

~bash flatpak run --command=sh app.fluxer.Fluxer \ -c 'getent hosts web.fluxer.app' ~ Result: ~text 2001:19f0:4000:174e::1 web.fluxer.app ~

7. Verify IPv4 and IPv6 HTTPS connectivity:

~bash curl -4 -I https://web.fluxer.app/ curl -6 -I https://web.fluxer.app/ ~ Both return HTTP/2 200.

8. Start Fluxer with Chromium's AsyncDns feature disabled:

~bash flatpak run app.fluxer.Fluxer \ --disable-features=WaylandWpColorManagerV1,AsyncDns ~

9. Fluxer now loads normally.

Stable Desktop 2026.920.144558 Linux 7.2.5-200.fc44.x86_64 (x64) Electron 44.4.1 Chrome 152.0.7977.78 Node 24.21.0 Locale en-US Flatpak: app.fluxer.Fluxer

Normal launch: ~~~text [Window] Loading app URL { appUrl: 'https://web.fluxer.app'/ } [Window] App main-frame load failed { errorCode: -105, errorDescription: 'ERR_NAME_NOT_RESOLVED', validatedURL: 'https://web.fluxer.app/' } electron: Failed to load URL: https://web.fluxer.app/ with error: ERR_NAME_NOT_RESOLVED ~~~ Screenshot: Fluxer remains blank/gray while Electron reports ERR_NAME_NOT_RESOLVED: image Flatpak has network access: ~text [Context] shared=ipc;network; ~ Host DNS: ~~~text $ getent ahostsv4 web.fluxer.app 45.63.21.197 STREAM web.fluxer.app $ getent ahostsv6 web.fluxer.app 2001:19f0:4000:174e::1 STREAM web.fluxer.app ~~~ DNS from inside the Flatpak sandbox: ~text $ flatpak run --command=sh app.fluxer.Fluxer -c 'getent hosts web.fluxer.app' 2001:19f0:4000:174e::1 web.fluxer.app ~ Both of these return HTTP 200: ~bash curl -4 -I https://web.fluxer.app/ curl -6 -I https://web.fluxer.app/ ~ Workaround that fixes the issue: ~bash flatpak run app.fluxer.Fluxer \ --disable-features=WaylandWpColorManagerV1,AsyncDns ~ Screenshot: Fluxer loads normally with AsyncDns disabled: image A direct hostname mapping also works: ~bash flatpak run app.fluxer.Fluxer \ --host-resolver-rules="MAP web.fluxer.app [2001:19f0:4000:174e::1]" ~ This suggests that the failure is related to Chromium/Electron's internal DNS resolver rather than general DNS resolution or missing Flatpak network permissions.