Does Home Sharing only work over wi-fi?

Question

This may seem like an odd question, but I think it may be the root of my problem. I have a network that uses three Devolo mains network extenders in various rooms (the house has very thick walls). All three Devolo mains plugs connect (via the ring main) to the router. An iMac, laptops, an Apple TV, iPhones, etc each connect wirelessly to these very happily.
However, no two computers (say an MBA and an iMac) in the same room, or different rooms, can 'see' the other in the normal way - i.e. by having the other device appear in the left hand pane of the finder window. They can, however, if I enter the IP address of the other machine manually. So this is irritating but not insurmountable.
What does appear insurountable though is that, in a similar way, iTunes cannot 'see' any shared libraries across the network. Because of the issue described above, I had assumed that both problems were probably being caused by some sort of issue with the way the Devolo boxes are configured. But then I realised that, even though each device is connecting wirelessly to the Devolo boxes, I don't actually have a wi-fi network in the same sense that I would if I had an Airport-based system...and if Home Sharing only works over wi-fi, this might explain why it doesn't work for me.
Apologies for the rambling question, but given the increasing popularity of these mains network-extender boxes, I feel I can't be alone in experiencing these issues. Can anyone shed any light?

Answer 1

The quick answer to your question is no, for example Home Sharing works over Ethernet as well. Strictly speaking Wi-Fi is not required and iTunes doesn't care either way.
However, I understand that the Devolo mains adapters have problems coping with this. If I had to guess, the problem might be an inability to carry the required bandwidth. The reason for this is that Airtunes is fairly demanding of bandwidth and if your wireless network's performance is degraded due to any number of variables, Airtunes is the first to suffer.
You didn't say what kind of computer or OS you are using but Home Sharing uses TCP port 3689 and UDP ports 123 and 5353 to communicate with shared iTunes libraries. Those ports need to be configured in whatever firewall or security settings you may be using. If you are certain you have those ports open on your shared computers then concentrate on the Devolo adapters. Perhaps they are in need of a firmware update or modification of some configuration setting.