Computer doesn't recognize Ethernet cable (From a router)

Maybe the Ethernet cable isn't plugged in the router's Ethernet port, firmly. All you need to do is to plug it in, firmly, in one of the YELLOW ports as the blue one is the Internet "intake" port.

Note: Once the cable is detected by the computer, a green light near the ethernet port should start blinking.

If the Ethernet cable is fully functional and firmly plugged in on both ends (computer's and router's), but your computer doesn't recognize it, restart the router by unplugging it from the power outlet and plugging it back in after a few minutes.

If your computer doesn't recognize the Ethernet cable from the router, it is possible that the router is turned off. Check the router's lights. If none of the lights blinks, then the router is definitely turned off.

All you need to do is to turn on (or plug in its adapter in a power outlet) and the issue will be resolved.

If the router's Ethernet port(s) is (are) dirty, the computer won't detect the Ethernet cable. All you need to do is to take a small piece of cotton (or a cotton bud), pour some isopropyl (rubbing) alcohol on it and clean the Ethernet port(s).

Note: If the indicators next to the port, which signal when a connection between two devices is established, don't blink after you have cleaned them, check out the other solutions.