回複：請問電腦上網速度突然慢了很多 ping yahoo time 總在700-800

Try ping other web sites, like bing.com, wenxuecity.com. If it is just yahoo that is having problem. It might be a yahoo server problem.

Then try ping your routers' IP address from your machine. You can use ipconfig /all to find your router's IP address, which is the value of "Default Gateway". If ping time is larger then 50ms, call your internet service provider.

If the ping router time is small. Then try power off your computer and your router, and wait for 5 minutes, restart them all. Try ping again.

If symptom persists, call your internet service provider.