Do you have a network switch or hub that you're using in this configuration? It sounds like you don't.
It sounds like you have just connected the two
LAN cards directly together with your
blue cable.
You can connect computers together like this, but you need a special cable. Yes, even more special than blue.
A standard Ethernet cable has all the individual wires running straight through, which is what a switch or a hub is expecting. If you don't have a switch or a hub, you need a cable that has the transmit and receive pairs crossed over... commonly known as a cross-over cable.
I haven't seen or needed one of these for years. They used to be fairly readily available when network switches were expensive. These days you can pick up a switch for a little over £10, so I suspect that use and therefore availability of these cables has declined. Your local PC shop might have one, or might be able to make one up for you.
Failing that, buy or borrow another cable, of any colour you like, and a £10 switch.