|I connect my first computer (laptop) using the Ethernet jack, and then set it up wireless, |
Do you mean, set up the wireless network on the wireless router using the laptop? Or did you mean, set the laptop up to connect wirelessly while it was connected via a network cable?
Try this, plug the first laptop back in to the router. Verify it's connecting to the internet properly and then open a command prompt window and type the following command:
Write down all the TCP/IP information for that laptop.
Unplug that laptop, and plug the second one in now (the one that didn't work) and open a command prompt window on it and type the above command.
Compare the TCP/IP information. The only thing that should be different is the actual IP address....and it is possible it may be the same as well but I'm more concerned with the default gateway and the DNS addresses. Those should be identical in both cases. If not, then ensure the second laptop is also set to get it's TCP/IP information "automatically" (ie: DHCP) and try again.