Currently Being ModeratedNov 8, 2013 10:33 AM (in response to Brian Smith5)
Resetting network settings should fix it.
I know on my iPhone/iPad - they both automattically connect to attwifi. I cannot forget that network since it is baked into the device somehow. But others have never been a problem.
Currently Being ModeratedNov 8, 2013 11:32 AM (in response to pdroth)
There is a way to stop the automatic connections to the AT&T wi-fi. When you're connected to it, look for a setting to switch in that network's page. It's similar to, although not the same as, the "Forget the Network" button. If memory serves, it's something like 'connect to this network automatically.'
Currently Being ModeratedNov 8, 2013 11:38 AM (in response to Brian Smith5)
Update: "Reset Network Settings" did not fix it. My iPad just joined the forgotten network on its own.
Currently Being ModeratedNov 8, 2013 2:48 PM (in response to Brian Smith5)
Further update: Changing the setting "Ask to Join Networks" did not fix the issue either. (This is not too surprising, as the problem is that the device is treating the forgotten network as a known network.)
Currently Being ModeratedNov 13, 2013 9:31 AM (in response to Brian Smith5)
Solved: It was iCloud keychain.
iCloud keychain includes wi-fi access points and passwords. (See e.g. http://gigaom.com/2013/10/24/iclouds-new-keychain-service-remembers-more-than-it -can-manage/ ).
Because my laptop was connecting to the forgotten network, the login information was populating to the iPad and iPhone, and the iOS was treating it as a known network.