One network PC ok : other no internet. Help!

Hello Kind People!
I decided to move things around within our home and change our wifi network back to wired network. Everything disconnected and reinstalled.

Two desktop PCs now cable directly connected to LiveBox.
My smartphone connected to LiveBox with wifi.
Problem:
One PC and my smartphone function well. So I do have good internet access with these devices.

However, although the other PC does connect to livebox (through http://192.168.1.1/ ), it doesn�t access the internet using either Firefox or Internet Explorer.
Any clues, please?
Thanks for any help

Maharishi

PS. Hope this is the right forum? If not, please advise

Start with the basics.

1. Does the network card show Ethernet connected e.g. LED on at both ends?
2. What are the IP address settings for the card in the operating system.
3. What does ipconfig /all display when run from the command prompt, i.e. IP address, subnet mask, gateway address and DNS settings?