Network disconnects while getting incoming call

Hello,

Whenever I make net calls from my laptop the network works fine but as I get any incoming call the network disconnects. It shows yellow exclamatory sign at the right bottom corner of laptop.
later I need to switch off and on the main power cable connected to router then it works fine but again if I get call the again gone case......I am the only person to use netwrok

Please help me!!!!

Regards,