Product: HP Probook 455 Operating System: Microsoft Windows 8.1 (64-Bit) It was worked earlier properly on this machine. There are two wifi routers in the house, but notebook is unable to connect. I got error message during connection, that it is unable to connect to network. Wifi routers are working, other devices can connect to these. Built-in wifi card is Ralink RT3290 and there wasn't any software updates installed to it. I tried to reinstall original driver too, but doesn't helped. I tried to modify DNS, it is 18.104.22.168/22.214.171.124 at this time. I tried to remove all the connections from the list, disable and reactivate wifi card, but nothing helped. I connected an USB wifi card too, it was worked for a while, but it isn't working at this time. I connected to a Huawei mobile wifi router, in this case connection is OK with built-in wifi card too.