This phenomenon is quite normal.
1, from the perspective of physical propagation speed, the core of the network cable is metal, and the propagation speed of electromagnetic waves in the metal is definitely higher than the propagation speed in the air;
2, from the point of view of signal transmission efficiency, WIFI radio signals in the air will encounter a variety of interference, while the network cable is a smooth way, from the point of view of transmission efficiency, the transmission efficiency of the network cable is also higher than wireless transmission. For example, both sides are 100 packets, one side along the network cable all the way to the end, the other side is in the air for a while to hit the wall, a while to hit the steel bar, all the way to the end only to find that a few packets are actually sent by other routers using the same channel, there is no way to go back and send it again, How can that be more efficient than a network cable? To sum up, it is very normal to connect fast with network cable and feel slow with WIFI.
The speed of WifⅠ is fast and slow, of course, and the installation of the network cable has a direct relationship, but now most of the network cable is spread by optical fiber, the general network speed is still OK, but sometimes I feel that the WiFi speed at home is relatively slow, and it may be the problem of the router. So usually when we choose the router, we must choose the transmission, the signal is relatively large, that is, the more antennas, the better the effect