The present invention is to provide a system for assisting a user in troubleshooting network connection problems, which includes a main terminal device (e.g., a computer) and a mediation device (e.g., a router) connected to the main terminal device and storing an assisting web page. Upon receiving a web page request instruction from the main terminal device, the mediation device redirects the web page request instruction to a website address. When the mediation device determines that itself is not connected to the Internet (i.e., a network connection problem occurs), the mediation device will send the assisting web page to the main terminal device. The assisting web page is displayed by the main terminal device through a browser thereof, so as for the user to troubleshoot the network connection problem according to the steps specified in the assisting web page (e.g., to perform a line inspection, a light signal check, etc.).