You may proceed with below troubleshooting and it shouldn’t take you any longer than 15 minutes.
1. Please standby computer/laptop to access to the internet and connection must be via LAN (cable) [Connect the LAN (cable) to the blue port at Cisco Router and direct to computer/laptop].
2. You may open any web browser such as Google Chrome, Internet Explorer, Mozilla Firefox and etc.
3. On the address bar, please go to http://192.168.1.1 and below page will appear.
4. Type the Username and Password as below. Then click OK. (These are the defaults, if you have done previous configuration on your router the password may be different).
Password: admin (or time123)
5. The router's web-based setup page should now appear. Please follow below steps for the configuration.
i. On the setup page, click the Wireless tab then click on the Basic Wireless Settings sub-tab.
ii. On the Configuration View section, click the Manual radio button. Choosing the Manual setup will allow you to adjust your wireless channel according to your preference.
iii. Leave the Channel Width set to 20MHz Only.
iv. Click the drop-down arrow for Channel, then select your desired channel.
Choose between 1 until 11 (Suggested 1,6,11).
v. Click Save Settings to apply your changes. Router will auto reboot and connection re-establish after few minutes.