I can't connect one of my LAN PCs to Internet

[mikac2014]

Here's how it goes. I have a standard router (I use ADSL Internet), and I had a PC connected to it. Everything was OK, internet worked like a charm, I used a normal LAN cable etc. Then I plugged in a second LAN Cable in LAN2 Slot, and connected the cable to my second PC. The LAN2 Light on my router was blinking. So I turned on my second PC, and the internet didn't work. Windows said it had an invalid IP Configuration. I checked, and the Internet on my first PC works great. I have nothing in my PortForwarding settings (currently). Should I try to manually configure IPV4 on my second PC or should I try something else?
Sorry if wrong Forum.

 

[boosted1g]

Is the adsl using default settings or modified settings?
Log into the ADSL modem and make sure DHCP server is enabled.

 

[mikac2014]

Is the adsl using default settings or modified settings?
Log into the ADSL modem and make sure DHCP server is enabled.

Problem solved. I changed the LAN port. Looks like I just needed to change the port to LAN1.