I managed to get remote replication working but it took trying a number of things to get it sorted. Thought I'd share in case it helps.
I set up CouchDB on a remote server (Debian) as a 'standalone' setup with the bind address of 0.0.0.0, if you use 127.0.0.1 I don't believe it allows external connections. If you go to the IP & CouchDB port you should see a JSON response.
For setting this up in Drafft I had to use the server's IP URL & port, so http://188.8.131.52:5984. I do have a domain set up on the server but Drafft didn't seem to like it on one of my computers, the other seemed to work.