How to create a wired gigabit connection?

Question

Computer networks

Internet comes to the apartment through the glass at a speed of 200Mbps. A twisted-pair cable 30 cm long comes out of the provider's router. This cable goes into a network outlet, from which a 15-meter cable goes in the wall into the same network outlet. A cable 20 cm long comes out of the socket into the network card of the computer. All 3 cables are of the fifth category and are crimped directly. The network card supports speeds up to Gbps. The provider's equipment supports the same speed. On Wi-Fi, the speedtest shows about 200 Mbps. For copper on the computer, the speedtest gives 91Mbps. What do I need to fix in the network architecture in order to get the required Internet speed over copper?

Answer 1

The easiest way is to take a known working piece of cable and replace it in order. When you find a defective one, replace it.
Well, or take a cable tester, there is a mode for checking the quality of the line.