The usual reason for the Wi-Fi dropping is that it is set to automatically find a free channel. When it ‘sees’ another Wi-Fi router on the same channel, it will change, and drop all the existing connections. Configure the wireless access point with a fixed channel. Only choose channels 1,6 or 11, but also confirm that these channels are legally available in your location. This will likely solve most of the issues with Wi-Fi but also check for possible sources of interference, such as a microwave oven, or other wireless devices that should not be there.
Best solution is to connect all the devices using wired connections. Wi-Fi is a convenience, not a robust networking technology. Find a way to provide wired connection for all of the users if at all possible and your problems will disappear.