having problems logging in local hosted openhuman core from UI

[Bertii1]

Yesterday I wanted to run OpenHuman on my home server and connect to it via Tailscale, so I went to the cloud deployment section, ran the docker run command, copied the auth key, pasted the URL and key, then pressed "Test Connection" — only to get the following error:

Failed to fetch

The URL format I used was:
http:///rpc
I then tried removing a slash, changing it to:
http://rpc
This time "Test Connection" returned no error, but pressing "Continue" still resulted in an error.
What could be causing this?