Does this home-network work using an Ethernet Splitter?

Solution 1:

Is this actually possible?

Technically possible, but not recommended.

If so, are there any performance implications of using an Ethernet splitter?

You will be limited to 100 Mbps Ethernet (100BASE-TX), as all newer standards (such as Gigabit Ethernet) require all four pairs of the Ethernet cable.

But other than that, a decent premade splitter should work reasonably well... at least better than home-made "split cables".

any ideas are welcome

Option 1: Put the router in the same room as the ISP connection is. Distribute the LAN from there, and have just a dedicated Wi-Fi AP/bridge at the center of the house – that way you'll only need one Ethernet cable going to it.

(The router can still provide Wi-Fi as well. Your devices will automatically roam between Wi-Fi access points if they have the same SSID. This might even give you better coverage than trying to make a single device reach every corner.)

Option 2: Use a pair of managed switches, at each end of the cable, which will be able to carry two 802.1Q VLANs ("LAN" and "WAN") tagged over the same cable. This "splits" the cable logically, not physically, so you'll be able to have a full 1 Gbps or even 10 Gbps Ethernet link. I'll try to find an earlier thread about this.

Option 3: If you happen to have coax cabling (for TV) in the same place, it can carry Ethernet data using MoCA or G.hn adapters, which I believe go at least up to 1 Gbps. (This option is probably slightly above "use a splitter".)