Dear All,

I did some research for days and test on my TMRND Black router/modem with my galaxy note.
Afer adjust some of the setting, it work fine on Whatsapp, Viber, Facebook app, Youtube.

You can try the below setting, hope it help you.

1.) Login to your router.
    Open Internet Explorer, type 192.168.0.1 in the address bar
    (192.168.0.1 is the default setting, unless you change the IP)
2.) Goto 'Wireless' Tab, Click the 'Advance'
3.) Change the DTIM to 1

If still got problem, Play aroudn the setting in 'Wireless' -> 'Basic':
(You need to change these setting to test around)
1.) Change the Channel to 8 or other number.
2.) Change the Band Width to 20 Mhz
3.) Change the Mode to 802.11BG or 802.11BG