network access via gnirehtet reverse tether does not work

Device OS and version: GrapheneOS RQ2A.210305.006.2021.03.02.10
Device model/manufacturer: Google Pixel 4a
F-Droid version (in the About screen): 1.11
F-Droid privileged extension version (if installed):

What did you do? (clear steps if possible)

On a newly installed GrapheneOS pixel 4a, which has never connected to wifi. F-droid is installed via adb. There is no SIM, so no cell data, and wifi and bluetooth are disabled. I run the reverse tether app gnirehtet. I verify that the Vanadium browser is able to load a website. Then try to update fdroid repos by swiping down on "latest" screen.

What did you expect to see?

I expect the app to load the repositories and show latest apps.

What did you see instead?

A notification pops up with message: Cannot update, are you connected to the internet? and the latest apps are not shown.

I have seen #2111, which suggests setting "Over data" to always use, but that did not work. I've tried every combination of "Over Wi-Fi" with "Over data" to no avail. Any clues?

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