Solutions:
First of all, make sure that the mobile phone is not overdue, and the current signal is good.
1. Check whether the data network logo on the upper right is normal (G/E/3G/H/H+/1x/EVDO/4G/4G+). Generally, the network speed of G/E/3G or H network is slow, so it is difficult to open the web page.
2. Try to switch data flow again or restart the phone; If the conditions allow the temporary replacement of other SIM card try; Confirm whether a single specific App cannot be connected to the Internet or all the software of the whole phone can not be connected to the Internet.
3. Check whether the Internet access function of a single program has been disabled in the built-in network assistant of MIUI, or whether it has reached the upper limit of the current set package traffic.
4. If other network management software has been installed, and try to close or uninstall it.
5. Reset APN Settings (Settings - dual card and mobile network - click the corresponding Internet SIM card-access point name (APN) - reset), and select "net" to try the access point.
6. If the above operation work, and if this issue occurs after the system has just been updated, and the problem has always existed, it is suggested to download the latest complete package to try.
7. Data can be backed up. Do not restore the backup after clearing the data. If abnormal, it is recommended to go to the after-sales center for inspection.