NB: This may not be peculiar to android 6.0 or whatsapp alone.

Here is the solution to the problem I encountered recently on a tecno w4. After installing the whatsapp, I could not get it to connect, I tried everything I could (changed apn and port settings, reboot phone, etc) but it still would not connect, until I did the following:

Step 1: Turn your data connection on

Step 2: Slide the notification bar down you will see a noufication (Daily usage) tap on it, an app called "hi manager" will launch.

Step 3: Tap on network management, a page will open that has a list of ticked online applications

Step 4, if 'whatsapp" ( or Bbm , badoo, etc )is unticked go ahead and tick it. Your whatsapp messenger will start working.

Many people need to see this, especially if you just got yourself a new China smartphone.

Thanks for this, It saved my app issues.

Thank you this really helped me.

Thanks for this !!!