I have not applied your patch, but I too am unable to connect to the internet on MDs or a win box that is downstream of the core on the internal network.
Rule #1 - Be Patient - Rule #2 - Don't ask when, if you don't contribute - Rule #3 - You have coding skills - LinuxMCE's small brother is available: http://www.agocontrol.com
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I am using the hauppauge MVP as squeezebox replacements.
You can connect some powered speakers or it has a spdif
currently its not plug and play (working on that though).
Before getting one of these check the forums- if I remember correctly only some revisions are compatible without an additional pxe server.