503 when two fediverse instances communicate with each other

[Tealk]

Hello all,

I have a Mastodon and a Mobilizon instance on 2 V servers and these behind the Nginx Proxy Manager. Now when I want to access https://rollenspiel.social/api/v2/search?q=@schnupperrunde@rollenspiel.events&resolve=true&limit=5 the Mobilizon instance from the Mastodon instance I get a 503
But from other instances outside my network I can access each of the two instances.
Does anyone have an idea where I could start?

[valon0388]

Hi. Did you ever get this error resolved? I'm trying to set up a self-hosted instance of Mastodon and having some trouble with the reverse proxy config. How do you have yours set up? I'll try and help troubleshoot if needed.

[Tealk]

I have assigned the internal ips to the domains via dns