Read this recent discussion.

by R. Proffitt Moderator - 4/12/12 9:06 AM

In Reply to: Can't change to WPA-2 by urchin16

http://forums.cnet.com/7723-13973_102-560420/wifi-disconnects-from-time-to-time-galaxy-tab-7-plus/?tag=contentBody;threadListing

It would be best to move to WPA-2 but if not, try the others and be sure of those WiFi channels.
Bob