Hello, dear, please try following ways :
1, first check whether network wireless devices operate normally; whether connection distance is within the valid range, whether the tablet is connected to the WIFI , whether the method of using tablet is correct.
2. Whether the network is matched with wifi band (2.4GHz in the communications field called ISM (Industry Science Medicine) the world's public use of the wireless frequency band, is free of charge can be used without the application. So to WLAN brought about by the The disadvantage is interference, because the WLAN work in the 2.4GHz band, some other wireless devices (such as Bluetooth, wireless mouse, etc.) work in the band will interfere with the WLAN wireless signal, resulting in the actual use of WLAN performance deterioration. Group developed a standard in the 5GHz band, 5GHz band is not so much daily interference, the band is very clean, under the same conditions, business performance is better than 2.4GH) you can look at these
3, check whether put the metal plate on the top of the metal, because the metal shielding the signal.
4, whether install the software (for example: anti-virus software), if installed, then there may be software conflicts, uninstall the software can resolve this problem.
5, if the above are not, you can try to solve by refresh machine. Note: refresh to use the correct method and the refresh machine to match the firmware.
6, refresh still can not solve, that is the hardware problem, please turn maintenance.
have a good day