How to install TP-LInk router TL-R402M?

ake sure that You have done everything during the configuration process:

1) Power ON Your router.
2) Connect ADSL cable to router ADSL port.
3) Connect PC / laptop via ethernet cable to router ethernet port.
4) Open web browser and go to: 192.168.1.1 (or 192.168.0.1, it depends)
5) Write default admin login and password (usually admin/admin, admin/password, admin/passwd - it's always written in product manual).
6) Turn ON DHPC server.
7) Turn ON WiFi.
8) Change name of Your wireless network (SSID).
9) Turn on some security functions (WPA encryption for example, however You should turn ON security when all devices will working).

Make sure that without security you have also only local connection - maybe You configured MAC filter or sth else that won't allow You to go to the 'internet'.