I use deluge on a headless server as a seedbox. The way to connect is via http, using the deluge-web service that comes with the deluge standard package in arch linux. As usual with every http connection, you should enable https whenever possible, just to get that basic security level, even though you (most of the times) will use self-signed certificates that will give you the typical security warnings when connecting.
For reasons I still don’t know (perhaps because the certificates I was using were quite old already), a setup I have been using for years now, suddenly started giving errors upon connecting that didn’t give me the choice to accept the security risks and connect regardless, so I had to re-generate the certificates.
It’s a pretty easy task: you just have to navigate to the deluge configuration folder where the certs are stored at:
And regenerate new certificates like so:
openssl req -new -x509 -nodes -out deluge.cert.pem -keyout deluge.key.pem
And then go back to the deluge web UI settings and reference them on the Preferences -> Interface tab.
Hope it helps, since it took me a couple of hours to figure it out!