Home Sharing over VPN I have a working home sharing environment (i.e., when I am physically in my home network it's working fine).

My Modem has the possibility to easily set up a VPN network (L2TP). It works flawlessly and I can connect with both my OS X and iOS devices. I get an internal IP address and I can access local resources.

But home sharing does not seem to work over VPN. Any solution?
It is not EXACTLY an answer to your question but might be helpful anyways. I am using a program called Slink. It forwards all Bonjour-traffic over ssh. This makes it really easy to connect to my home-network. You get a list of services like Plex, iTunes, filesharing, screensharing, printers, and so on. You can also easily browse the web (via firefox) over this connection as well. You don't get to send all traffic through Slink like a normal VPN thou. 
I have used a number of VPN-solutions, but this made everything much easier. Hope it helps. It is not free, but well wotrh the money in my opinion.