In theory, you could have a relay for each of the 8 Ethernet wires, and programmatically control that.
But... you could also set up an OpenWRT router and if you can't configure IPs in non-conflicting way, you could turn particular network interfaces on and off as it's basically a Linux box. Note that most consumer routers compatible with OpenWRT usually have only two network interfaces, even if they have multiple ports for one of them.
Comments
In theory, you could have a relay for each of the 8 Ethernet wires, and programmatically control that.
But... you could also set up an OpenWRT router and if you can't configure IPs in non-conflicting way, you could turn particular network interfaces on and off as it's basically a Linux box. Note that most consumer routers compatible with OpenWRT usually have only two network interfaces, even if they have multiple ports for one of them.