Problem with CG3000D-RG Wifi

Hi,

Sorry if it is not he right place to post this message.

I bought a Modem Router (CG3000D-RG ) 3 weeks ago and it was working fine till yesterday. that a guy from ISP came and he hard reseted the device. After that the wifi light is off and the router is not working. I tried many things including hard reseting it again. and no solution yet.

I can connect to internet using cable. and the funny thing is when I remove the coax cable from the device, the wifi starts to work! but when I connect it back, as soon as internet gets to work, wifi shuts down! it's like if I can have either internet via cable or wifi without internet!!!!

also, when I'm using internet with cable, I can not login to 192.168.0.1, I need to remove coaxial cable first which means no internet, then I can access the device management web application.

any solution is highly appreciated.
Thanks