Notebook Internet access 5G malfunction

A few days ago, there was an Internet failure reported to me. When I went to the scene, I saw that a laptop was quite tall and high. The network card model was Qualcamera Atheros. A certain version of Qualcomm. The surrounding Internet was normal. Only his laptop had an Internet card broken. At first, I felt that it was a computer problem. However, in the spirit of the savior who would not go to hell, I gave him an external wireless network card. As a result, the computer flew freely in the network. It seemed that it was a network card problem. But check the network card is also a more serious ah, how can this be??? Check that the network card band is 5G, switch it to 2.4G and the result is normal. Record it here. Need to change wireless mode 02- 11g, use 2.4G instead of default 5G

Finally, I would like to emphasize that there is no problem with laptop 5G Internet access here.