PuTTY: Portable Firefox + SSH Tunnel

I have followed the guide here: https://portableapps.com/node/6663 to forward port 443 on my router to port 22 of a Fedora Core 6 box running OpenSSH. I am using PuTTY Portable of course to connect to it, and it is working fine as far as ssh goes.

As said in the guide, i have forwarded port 5678 to go down the ssh tunnel and set portable firefox running foxyproxy to use that as a proxy.

However, it appears it cannot resolve host names. I did the about:config thing as said also. I know the ssh proxy is working because typing localhost in portable firefox gives me the webserver running on the Fedora computer, which is not port forwarded. I can also type the LAN router address and get a login window. Seems that i can browse my network, but cannot get out to the internet. Lynx works in ssh though, so i know ssh has internet access.

I will test just using IP addresses and changing the DNS servers on the server to OpenDNS rather than the router which then points to the ISP's DNS.

Does anyone know what is causing this or whether this will fix it?

edit: in the guide when setting up the proxy if required, which it is (igate:8080) it says nothing about whether to change it from Auto for "Do DNS name lookup at proxy end" Im assuming you would always want this to be yes providing you are not browsing intranet sites?

edit2: I have tested it again. I definately have internet access, as i can visit googles IP address. However, even changing to opendns doesnt help. I still don't know why it can't look up domain names when lynx can, i can do local domains, and i can access the internet.