No Internet when another Android device is connected to router Like the titles says, i have a weird problem.
I have a brand new device A (Android phone V4.2, manufacturer is called "Vivax"-not very popular outside Europe), which is having problems accessing internet.

Internet works only if there is no other smartphones connected to router.If the other phone (some older Samsung) is connected, there is no internet access on the device A.If i disconnect the Samsung device, turn wifi off and back on on device A, it can browse internet.
But if the other phone is connected, there is no internet access at all.

I checked the router and i think it is using WPA2 encryption.Also, there is no IP address conflict.

Anybody have any ideas what could be the problem?
by reserving I guess uboat55 means to .. suggest the use of static IP address. you can configure your router to work with static IP address instead of a dhcp service.which I also feel should do the trick .

configure your router with fixed IP address and latter use that IP address.

or you can even try to assign IP address directly to ur device A. without changing any thing on the router part.

just remember the IP address range. 
eg 
192.168.1xx.xxx to 192.168.255.254 

and chose any one IP address within that range .

and remember the default subnet I.e 255.255.xxx.xxx or something similar 

and the router IP address and use this on ur mobile .