Remote desktop giving me bad gateway

[Hortoristic]

I have a dyndns account that works for many things - but when I tried with Obi - it actually brings up some of the Obihai web page, but I'm getting

"502 Bad Gateway - REsponse Error, a bad response was received form another proxy server or the destination origin server."

My local IP for OBI is 192.168.0.140 - in port forwarding, it is the only port 80 I have.

Some other port forwarding things for Sabnzbd and Sick Beard are working ok - so I know the port forwarding on router is ok.