I can connect to domo with workbench versions 2 and 3, however when I try to add the server connection in workbench 4 it throws up "an error occured while sending the request. If you are behind a proxy, make sure you can browse to 'mycompanyname'.domo.com"
I am behind a proxy and I can browse to 'mycompanyname'.domo.com. I noticed that version 3 has a proxy tab when connecting, however I left it on default which was "use proxy settings" and was able to connect just fine.