I have experienced this when lemmy.ml was having issues. my instance was aware of the community existence but because whatever was happening with lemmy.ml when i tried to access the community (for me was startrek) it couldnt fetch any post data.

my instance then took a few hours to retry (best guess as i have no clue how the protocol/process works) and now all is visible.

I also noticed that that this was because i was the first person on instance to attempt to access the !startrek@lemmy.ml.

(edit for formating)

I saw the same issue, but would like to provide some additional information (for my case): I searched for https://lemmy.world/c/mildlyinfuriating on my instance. According to https://join-lemmy.org/docs/en/administration/federation_getting_started.html, my expectation was I’ll see the community within a couple of seconds.

My lemmy-log shows

> lemmy_1 | 2023-06-12T15:14:49.089405Z ERROR HTTP request{http.method=GET http.scheme=“http” http.host=lemmy.pathoris.de http.target=/api/v3/ws otel.kind=“server” request_id=7c0dd0ef-2766-4e69-b9de-53d1459556ff http.status_code=101 otel.status_code=“OK”}: lemmy_server::api_routes_websocket: couldnt_find_object: Request error: error sending request for url (https://lemmy.world/c/mildlyinfuriating): error trying to connect: dns error: failed to lookup address information: Try again

My setup is based on docker-compose, https://join-lemmy.org/docs/en/administration/install_docker.html

Any ideas?

EDIT: It might be Centos 7 issue with default configuration or something I did in the past :-( I connected to lemmy_1 via docker exec and wasn’t able to initiate any outgoing connection from within the container. Seems I’m filtering it somewhere.

Federation takes time. I had the same problem federating content to my instance, but it should start to populate eventually. If you control the instance, you might try upping your worker count. It defaults to 64. I set mine to 128 and it seems to be doing better, and lemmy.ml just set theirs to 512.