I cannot use any browser with VPN turned off using mobile internet, but I can use other apps, such as BBC or Viber. I also can access the internet via Wi-Fi with VPN turned off. I have resetted APN settings many times, but it will not work. I cannot turned off proxy because there is no such an option. The proxy section is blank. When I fill in the blank with some random letters, and then blank it again, the internet begins to work, and after a few searches on the browser stops. Actually, when I change some other sections of APN the internet starts working, but then stops. Tell me please what is wrong. I am clueless about whether or not the problem is with the tablet or the mobile data provider. Because when I put a SIM card from a different provider into my tablet, it worked. And when I put my SIM card into another device, it also worked in that device. I called the company for help. They say that my APN settings was out of order. They sent me new ones. That also didn't solve the problem I have even resetted the tablet to factory settings. To my chagrin, it hasn't worked.
Navigate to settings>system>reset options click on "Reset Wi_fi, mobile & bluetooth.
This will however reset your your phone network settings
I had experienced a similar situation and this was the only solution that worked for me.
Did this work for you?