My range extender connected to main router but no internet
I've done setup my wifi range extender (TL-WA860RE) and the signal LED is green. Which means it should be in good connection. But every time i try to connect to my extender, there's no internet connection. I've checked in the app and I found that my phone connected to the ext and the ext connected to the main router well. But still there's no connection.
After several times i tried to reset the extender and re-setup my extender, sometimes it works. But there's no internet again later.
I'm sure that I use correct main router's password while setting up my extender.
Please tell me what should I do to fix this. Thanks.