Mobile data problems and computer connection problems are the two main reasons why you may not be able to send and receive messages on the WhatsApp Web.
Problems of telephone connection or mobile data
Your session on WhatsApp Web is an extension of WhatsApp on your phone. WhatsApp Web connects to your phone to synchronize messages, so you can see all messages on both devices. The first requirement to use WhatsApp Web is an active WhatsApp account on your smartphone.
If you can not connect to WhatsApp on your phone to send and receive messages, then you can not use WhatsApp Web. Open WhatsApp on your phone and try to send a message.
Once you can send a WhatsApp message from your phone, try using the WhatsApp Web again. If you still have problems sending or receiving messages on WhatsApp Web, there is probably a connection problem on your computer.
Note: To reduce the data usage charges on your phone, we recommend that you connect your phone to Wi-Fi.
Problems connecting to the computer
Just like you use WhatsApp on your phone, you must have a strong and stable Internet connection on your computer to use WhatsApp Web. If you see a yellow bar at the top of the chat list with this "Computer not connected" error message, verify that your computer's Internet connection is active. If your computer's Internet connection works normally and you can not send or receive a message on WhatsApp Web, first update the page.
If the problem persists, you must log out and log in again to reactivate your web session
Problems in certain wifi networks
If you use WhatsApp Web on a managed Wi-Fi network, such as your office or university campus, your network could be configured to block or limit connections to WhatsApp Web. If the WhatsApp website notifies you that you are on a Wi-Fi network that prevents the WhatsApp Web from working properly, ask the network administrator to divert traffic to web.whatsapp.com, * .web.whatsapp.com and * .whatsapp .red.
Important: You must use the latest version of Chrome, Firefox, Opera, Safari or Edge as a web browser to use WhatsApp Web. Other browsers such as Internet Explorer