This situation is generally due to the installation of some domestic optimization software for "optimization" or "garbage cleaning", resulting in the network card driver is disabled or lost.

You only need to uninstall the optimization software and reinstall the driver for your NIC to solve the problem.

If you have a wireless card, and you still can't solve the problem, you can try the following methods:

1, Device Manager, right-click on the wireless card - Properties, change the 802.11N, the default is 20 MHz, to 20/40 MHz.

2, open the network and **** enjoy the center - the upper-left corner of the - Manage Wireless Networks, the relevant icon will appear, change the previous wireless network, and the driver will be displayed on the screen. icon, right-click the previous wireless network - delete the network.

3. After the deletion, reconnect the wireless network, enter the username and password, and then in the window that pops up, make sure to select the public network.