Article in English: This may seem like a useless suggestion, but restarting your computer is often the easiest way to fix a vast majority of the issues you may be having. A simple reset will clear out bad settings which could be causing your connectivity issues, and if it doesn't help, it only took a minute. Restarting your computer will often also turn back on your Internet adapter if it was off. Many laptops have a switch or button that turns the wireless adapter on and off. If you've accidentally pressed the button, your computer will disconnect from the network. Press the button or toggle the switch to turn your wireless adapter back on.  You may have to hold the Fn button in order to be able to press the Wi-Fi button. Skip this step on a desktop computer. The easiest way to do this is by unplugging both your modem and your router from their respective power sources, waiting for a few seconds, and plugging them back in. Like restarting your computer, this can solve the bulk of minor Internet issues. A soft reset causes your router and modem to clear their respective caches and refresh. You can usually perform a soft reset by pressing a power button on the front or side of your router.  Many modems can also be soft-reset in this manner. In some cases, you can soft-reset your network by opening your router's page and clicking a Reset button somewhere in the "Advanced" or "Power" options. A hard reset causes your router and modem to forget all of your settings, restoring the network to its factory settings (including the factory network name and password). To perform a hard reset, you'll press and hold the "reset" button on the back of the modem for around 30 seconds, allow the modem to reboot, and perform the same step on the router. In most cases, the "reset" button is a recessed button on the back of the modem and router, meaning that you'll need to use a pen or a paperclip (or similar) to press the button. Sometimes your computer or smartphone is too far away from the checkpoint to connect. Move closer to your router and...

Summary in Vietnamese:
Khởi động lại máy tính. Bạn cần chắc chắn rằng bộ điều hợp mạng không dây (Wi-Fi adapter) của máy tính xách tay (laptop) đã được bật. Khởi động lại bộ điều giải (modem) và bộ định tuyến (router). Tiến hành thiết lập mềm (soft reset) lại mạng. Tiến hành thiết lập cứng (hard reset) lại mạng. Đến gần bộ định tuyến hơn. Bạn cần chắc chắn rằng giữa mình và bộ định tuyến không có chướng ngại vật. Thử sử dụng cáp Ethernet.