This is caused by the sameSite cookie setting. If you change https://github.com/Fallenbagel/jellyseerr/blob/develop/server/index.ts#L165 to false requests inside an iframe from another domain should work. Keep in mind that this completely disables CSRF protection.

Here's a patched jellyfin-web that additionally renders custom menulinks as iframe allowing easy integration with Jellyseerr

Wops.. sorry for that spam

Hello @sundermann
I did try changing the argument to something like :
sameSite: settings.main.csrfProtection ? 'strict' : 'lax', to samesite: false,

I still can't connect.
Have I made a mistake?

Hi @Ruakij no problem for spam

Thank you

Hello @sundermann I did try changing the argument to something like : sameSite: settings.main.csrfProtection ? 'strict' : 'lax', to samesite: false,

You need to set it to 'none' otherwise its left unset and a modern browser will automatically either assume 'lax' (in case of chrome) or 'none' (in case of firefox).

And even though 'lax' sounds nice, it actually only allows a few edge-cases blocked by 'strict' (like after being redirected from another site, even if you clicked the link yourselr)
It is unfortunate there isnt an option to specify which origins a cookie is allowed from.

Feel free to simply cherry-pick my commit, i fixed a thing, but now it should work nicely.

Thanks for your feedback
I tried ‘none’ too, without success.
When I try to connect through the iframe I always get error 401 related to connect.sid

I have also tried to host Jellyfin and Jellyseerr on the same server (192.168.1.1:50**) without success.