Thanks for pitching in JuicyFox94 . For the connectivity, I used the "public" names for the various server
(e.g. we set clearml.internal.domain.name, clearml-apiserver.internal.domain.name and clearml-apiserver.internal.domain.name)

So in the agent values.yaml I set the parameters:
# -- Reference to Api server url apiServerUrlReference: " ` "

-- Reference to File server url

fileServerUrlReference: " "

-- Reference to Web server url

webServerUrlReference: " " `to the actual domain name.

Should I try using the internal kubernetes domain names instead, like
clearml-fileserver.clearml.svc.cluster.localinstead?