There are basically two types of IP address - one that your ISP assigns which is usually dynamic for the home user and in theory, can change whenever you switch the machine on.
This is the one you will see when you use an IP lookup program.
The second is what the router's DHCP assigns to whichever adapter and machine is being used and usually starts 192. and depending upon the DHCP range that the router uses, can be from .2 or end with anything up to .255 but rarely goes above .254
This is the IPv4 address which is above the Subnet Mask in ipconfig /all
Lower down you will see the Default Gateway which is the router's IP address and that will be .1
Regardless of changing the DNS servers, if DHCP hasn't assigned itself or any or the computer's adapters with an IP address the you will not connect.
When the computer fails to obtain a DHCP address, Windows will assign it with what is known as an APIPA address (can't remember what stands for so you can Google it
) and that will start as 169.
When you were unable to connect and did an ipconfig /all you may have seen that as the address for IPv4 Address.
This address can also prevent you from logging into the router because of lack of connectivity.
I've never done port forwarding and can differ with the UI of the router used - while a Google will probably give you the basics, your ISP should be able to walk you through the UI but Port 80 is usually blocked by the router's Firewall.