Internet disconnects when i connect mobile/tablet via Wifi

Hey guys, i am on DataOne BSNL.
My D-link Wifi Router is connected to the PC.

Now this problem started just recently.

my internet is ok, normal, good... no problems.
But whenever i connect my cellphone or tablet or any other wifi divices to my Wifi, i start getting disconnected
See the picture--

*i59.tinypic.com/2lliqoh.jpg

As soon as i switch ON my phone wifi, ping starts going up till it gets disconnected. When i switch off wifi on my phone, steadily ping drops and become normal again.

This problem started only recently >_<

Pleas help

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UPDATE
Ok this problem happens only with my Tegre Note 7 Tablet. My phones are not creating problem. When i switch on Tablet's wifi, the entire internet of our home messes up

Maybe there is some overlap of Wifi channels with your neighbours? Try this: inSSIDer by MetaGeek and see if there is overlap(post a screenshot if you can)