Opening note: Please watch your language. This is a family friendly forum.
15 meters is well within the Ethernet cable limit of 100 meters.
Try swapping your cable with another known working cable - any length that will reach.
Switch router ports - just to test and try.
Are any other network devices having connection problems? Ensure that the problem is just your gaming PC.
Who manages your network's router? You may need to check the router's logs (if available and enabled) for error messages/codes.
Be sure that your network adapter is fully and firmly seated in place.
Run pingpath and tracert via the CMD prompt. Try several times to determine if the problem inside or outside of your network.
Goal is to narrow down the...