Don't panic! First, please check your account page to see if your Chinanetspeed subscription has expired!
If your chinanetspeed subscription is active, try connecting to the backup diagnostic wifi - login and password details are found on your account page. Please note that the built-in wifi is NOT intended for long-term use as the maximum speed is significantly slower (30Mbps vs. 200Mbps). You'll receive much better performance via your own wifi router.
If CHINANETSPEED-XXXXX wifi is working, but not your own wifi router, then the problem is likely one of the following:
1. USB ethernet adapter - try changing the USB port
2. Ethernet cable - try switching cables if you have a spare
3. Wifi router - try restarting the wifi router
Finally, if Chinanetspeed wifi is not working, check your local internet connection to see if any Chinese websites are loading (Baidu, Taobao, etc). In many cases, the internet subscription to your local China connection may have expired.