How to replace the RJ45 connector?

paulosantos.phs  I assume you are talking about your LAN port. It may be possible. Take it apart using something like this video and see how it is connected. Your port should be soldered to the motherboard, so you will have to desolder it. Hardest part will be to find a replacement. Get a pair of calipers and measure the actual port. Then go to mouser.com or digikey.com (aliexpress.com may be another option)or similar sites and see if you find a matching port.

If you absolutely can’t find a repalcment. you could always solder a LAN port pigtail directly to the board.