Hi all,
I have a geoserver 2.25.2 installation (docker) and if I make a GetCapabilities request to a specific workspace, it takes 4 minutes to return the response and sometimes the request is aborted (status 200 ns_error_net_partial_transfer). The same request to another workspace works perfectly. I have tried both from browser (Chrome, Fiorefox and Edge) and a client like QGIS.
If it was a proxy or firewall issue, I would have the same error with other workspaces. Could it be due to one or more layers published in the workspace?
You could try the generic https://geohealthcheck.org which is cute; it tracks availability (and you could set it up to monitor individual layers). Keep in mind this is an external monitoring system and does not help identify performance or configuration improvements.