Hello kalvin,
* Check whether having any damages of cable
* There is two types of cable configuration
1. Crossover : use for Router,console DCE interconnect
2. Patch : use for peer to peer connection
[http://www.bb-elec.com/Learning-Center/All-White-Papers/Ethernet/Ethernet-Cables-RJ45-Colors-Crossover/EthernetRJ45A.gif|Here] you can find pin identification and cable type identification
You can find any cable broken or loss connectivity using multi meter or cable tester
RJ45 having 4 ground cables (White mixed) even if one of them broken still you have can communicate but full speed will not offer by Ethernet
also data transfer speed also depend on CAT cable type
[https://en.wikipedia.org/wiki/Category_5_cable|More info]