problem with internet

[LukasQ9]

Hello.
So i have little problem with my internet, i bought new mobo everything is just fine but when i plug ethernet cable directly from modem to mobo internet works but when i plug it with enthernet extension from 2floor where is my modem and my pc in first floor there is not internet. I tested the extension it is working, extension worked with my old mobo. Maybe anybody would know what's wrong and help me. Maybe i must enable something in PC?

 

[blindvi1]

Wait, what? explain the situation again please. Are you taking the other end of you modem cable (your Mobo im guessing is your ISP supplied modem, if not, please clarify and identify it) and connecting it to your PC upstairs via Ethernet, is that what you are asking? Also what type of cable are you using and how is your wiring laid out.

 

[LukasQ9]

Wait, what? explain the situation again please. Are you taking the other end of you modem cable (your Mobo im guessing is your ISP supplied modem, if not, please clarify and identify it) and connecting it to your PC upstairs via Ethernet, is that what you are asking? Also what type of cable are you using and how is your wiring laid out.

So basically i have modem upstairs and my pc downstairs there is extension cable in my wall when i plug through extension cable there is no internet, but when i bring my pc upstairs and connect it directly from modem without any extension there is internet connection. I checked the extension cable it's working with my old mobo. But with new there is no internet.
By mobo i mean computer motherboard (mainboard)