The server is set up as http, but I reverse proxy it as https.

The problem boils down to this. The server thinks it's on http, but its really on https via a proxy. And therefore the agent tries to reach the api on http.

@<1547028017774071808:profile|LazyGoat32> , the agent can only communicate using HTTPS with the server is the server was set up with SSL termination (i.e. supporting HTTPS).
HTTPS support is not part of the basic server set up and can be added on top of it (see the documentation here , as well as several threads on this both here and in the clearml-server github issues).

The server is basically oblivious to https - any reverse proxy implementing SSL termination should handle HTTPS and forward the decoded requests to the server upstream using HTTP - if your reverse proxy doesn't do that, than you're effectively no doing SSL termination but simply forwarding whatever you get to the server, and the server won't handle HTTPS

Why do you need to specify the 443 port?

See here on how a user did that in the past: None

So probably there's something wrong with the proxy?

I shouldn't have to, just trying to be as verbose as possible so it works. I don't think the proxy is at fault because it works over the same proxy but http instead of https, and it works with the same proxy for the web endpoint, just not for the api endpoint.