Home Sharing over Ethernet

some routers keep 2.4Ghz and 5Ghz and ethernet on separate networks unless the user go into the routers settings and bridge them

if you can ping it and if the required ports are allowed in the router it should work it's how most of us run the setup

TCP and UDP ports and protocols used by Apple TV - Apple Support

no but you can connect a ethernet switch to the router and connect the appletv and the mac to the switch then you would not have router issues in the equation as the switch would work for the 2 to communicate even if you disconnected the router

You could try re-setting the powerline connections - I've had an issue where for whatever reasons, my powerline adopters stopped talking to each other. I don't know how the reset is done on a Belkin.

OK. Couple of questions, with apologies if you've been rond this before:

1. If you switch of wifi at the wifi router, does the Apple TV connect (in the TV network settings)?

2. Could this be a DHCP issue? I had some significant DHCP issues because I had my wifi set up oddly (I was extending a wifi network instead of cloning - this shouldn't affect you, but I thought I'd mention it). If you have more than one wifi router, this is definitely worth a look

3. Have you tried connecting another device to the same cable in the same location as the TV?

Ok, update, I swapped some cables round to see if there was a dead cable. There's not, however if I run a really long cable direct from the iMac to the router, this solves the problem. Previously it was talking to the router via a Belkin powerline. Previously this never used to make a difference although now I am guessing the Powerline adapter is changing the subnet mask or something so it's not recognising the end machine.

You can figure out this part of it easily by seeing what IP address and mask are assigned to the iMac in each case. Compare to the router's address/mask and that of the iMac.

Are you still in the state where, if you take the powerline out of the setup, that it works with just the Ethernet connections? If you could include some topology pictures of what works and what doesn't, that might help.

I'm not familiar with how Home Sharing works under the hood, but I suspect that the shared resource (Mac) advertises its existence via Bonjour / MDNS. It may be the case that those multicast packets are not getting to the ATV with the powerline there, but the only way to tell would be to use a traffic sniffer like WireShark (but I'd want some confirmation that Home Sharing uses Bonjour before going that route).

OK, I'm going to back up a few steps just to be sure I'm not making any wrong assumptions. My apologies if this seems tedious but since I'm not looking over your shoulder, I just want to make sure I'm working with the correct information.

When you say "it doesn't work" on the ATV, what exactly does that mean? Does the iMac share show up at all under Computers on the ATV? If so, what are the next steps you take and what happens?