504 errors with Webdav sync

[ghost]

This is a copy of #846

I'm trying to use superproductivity with Koofr.eu on all my devices. I'm also using Koofr cloud storage for some other Webdav applications.

I was able to connect to Koofr with the desktop superproductivity app but not through the android app.

I have followed their instructions at their documentation about webdav services but without success for the android app.

I'm using superproductivity 6.3.3 on android 10.

Sync settings:

[x] Enable syncing

Sync interval: 1m (for tests)
Base url: https://app.koofr.net
Username: >My koofr email<
Password: >My Koofr application password<
Sync File path: /dav/Koofr/my/custom/file.json

file.json already exists from my tests with the desktop app.

When I save the settings and wait I get the following message:

The page at "https://app.super-productivity.com" says: no remote data found. Upload local to Remote?

Which is not correct because the file exists from the desktop sync.

If I click OK I see the errors pop up:

Unknown Sync Error: Error: Request failed with status code of 504
Unknown Upload Error: (Settings correct?): Error: Request failed with status code 504.

I contacted Koofr support and we verified credentials (the info I am using above is correct according to them) but we couldn't make it work and they advised me to contact superproductivity team as they thought the error might not be on their end.

[johannesjo]

Thank you very much for copying this over. Apparently you are not the only one having this issue:
#851 (comment)

I can't help you with any specifics, because I am not familiar with Koofr, but I strongly suspect that you somehow need to whitelist https://app.super-productivity.com to gain access to your WebDav server.