I have a very basic small network with 1 2012 Essentials server and 5 Dell laptop clients 8.1 Pro 64bit.
When the clients are connected via the wifi using the BT router I get good traffic to and from the server and good web traffic.
When they are connected via the Ethernet (intel i218-lm) I get good pings but v v v slow data transfer to the point of not really connecting.
I have made sure all drivers are up to date but still no luck.
I have double checked the cables and all seems fine.