DLink

Open Internet Explorer window and in the address bar type in 192.168.1.1
Type username as admin and password as admin as well and click on the Login button
In the next window click on the Setup tab and then the Connection button under WAN Setup. Depending upon the model of your D-Link router any one of the two screens below will appear.

Or

Configure the following settings in the window:
Type: Set the connection Type to PPPoA
Name: Type a name for the connection. (for example Talktalk)
Options: Keep NAT and Firewall checked.
Encapsulation: Set to VC, make sure LLC is not selected.
Username: Type your account username
Password: Type your account password (make sure there is no case or spelling mismatch)
Keep Alive: Leave default values, do not change.
Max Fail: Leave default values, do not change.
MRU: Leave default values, do not change.
MTU: Change to 1458
Set Route: Check the option to enable set route
VPI: 0
VCI: 38
QoS: Leave default values, do not change.
PCR: Leave default values, do not change.
SCR: Leave default values, do not change.

Now click on Apply. (Please note that it may take upto 5 minutes to apply the new settings)
Now click on the Status tab on the top and then Connection Status button on the left side. Connection information will be displayed under the WAN section

Incase the status says disconnected, please note the Disconnect Reason. If it is related to username or password please go back to the earlier step (under Setup and Connection) and change the username and password there.
Click on the Tools tab on the top, then click on System Commands on the left. Click on the Save All button to permanently save the changes

Once you see the confirmation message that the settings have been saved permanently, close the window. You can now use your browser to connect to different websites.