@Jay_Bhatia 

You can try modifying the wireless channels the wireless bands use on the C6, then set up the WDS on the 841. 

@Tony thanks for your response but i tried that already i tried channel no 1,6,11 but no help situation is same all the time. I also tired updating my router but no help i also got the replacement of the router but no help i feel there is some issue with the configuration on the archer C6 but not sure what is creating issue i have not done any special configuration on archer C6 that could create the issue hope any one can solve my problem 

@Jay_Bhatia 

You had mentioned the 841 works fine with other routers, but I would bring the 841 into the same room of the C6 and test that way. Make sure the 841 has its own unique SSID when testing.

If you look below your router, what is the country code? Ex. (US) (UK) (EU) etc.

@Tony i have tried keeping my 841 next to my archer c6 and yes 841 has its own unique SSID