Dropping out of networks can be caused by various things: faulty device, transmission rate, distance between client and Internet source, configuration, etc. In your case, you will have to check all those things.
-
Open the management software and reset everything, including settings, networks, adapter, etc., then reconnect.
-
Go to Device Manager (Start > Run > devmgmt.msc) and check the driver's installation. Re-install it if it appears in yellow.
-
Check the router and increase its transmitting power to 100 %.