What the poster means is that when there are many people, the Internet speed will be average. When there are few people, the Internet speed will be faster if only one person uses it. The purpose of the poster is to improve the utilization rate of broadband. In fact, to put it simply, the poster wants "elastic broadband". This requires the router to have QOS function. Generally, routers have IP flow control, but the principle of IP flow control is not the same. Similarly, it can be said to be just a simple QOS, which is a small part of QOS, so the poster wants to buy one with QOS.

The latest generation now allows you to specify the data flow direction (i.e. traffic shaping), which is more advanced than elastic broadband