First make an internet speed check with LNS tool, then identified the slow factor.
1. Virus infection
This situation often manifests in Internet Explorer browsers. Users may try to open a page, but have to wait a long time before it responds. View the process in the Task Manager (press Ctrl + Alt + Del and select Task Manager). If the Performance tab indicates the CPU usage rate is 100% and memory is full, the PC is confirmed to be infected with a virus/viruses. In this case, you do not have available memory to open new programs. It is necessary to find out which application is greedily taking up CPU resources.
Once you find the application in question, end the task. If you cannot end it, you have to restart the PC and run it in Safe mode to delete the application. You also need to shut down the application in the registry dialog box (click Start > Run, then enter "regedit"). Click Edit > Find, enter and find the name of the program, and right click to Delete. Perform the search several times to ensure that it is completely removed. Anti-virus software and security tools are more for the prevention of viruses, but when a PC gets infected, the best solution is to manually delete it.
2. Proxy server connection
For security reasons, some browsers are preset with a proxy server (Control Panel > Internet Options > Connections > LAN Settings > Use A Proxy Server For Your LAN). The proxy server does not affect certain networks e.g. QQ Messenger, because QQ uses 4000 port, and accessing the Internet uses ports 80 or 8080. This is why users can sometimes log-in to messenger, but cannot open a web page. The proxy server is generally not very stable. If the problem continues, it is advisable to turn off the proxy setting.
3. DNS server interprets error
DNS is the Domain Name Server, which is a tool that transitions domain names into the IP addresses that computers recognize. Sometimes the network service provider may be down due to router problems. When the DNS server interprets error, you can call and consult your Intenet Service Provider (ISP), who can reset the router by flushing the DNS.
If the PC's network card cannot search the DNS server address automatically, you can try using a specified address via Network Attributes (Control Panel > Network and Dial-Up Connections > Local Area Connection > The Right Attributes > TCP/IP Agreement > Properties > Use The Following DNS Server Addresses). For example, Google DNS 8.8.8.8 (primary) or 8.8.4.4 (alternate). It may also be a good idea to update the network card software driver or replace the card entirely.
