This issue could be a Power configuration problem. What type of WiFi adapter does your computer have? Check the Power settings to make sure that your USB and WiFi and Network adapters are set to Never turn off.

One way to check to make sure it is not your WiFi router/modem that is causing the issue would be to connect the computer to the router using a network cable. If you get the same issue when connected using a wired connection, it could be a router issue. I have all of my network equipment and computers on UPS systems, so that power drops do not cause problems.