If you're using a home router shared by more than 5 users accross all direction and floors you may run into problem like that.
I have recreated the wifi interface in the Ant.
When I scan for the network the signal is 70%+.
When I click join the network I get 0% signal.....
I had the same problem with one of miners in my last batch of five S1's. One seen the wifi network fine but it was a 50/50 chance trying to get it connected. I finally change that miner out with a different S1 that was on an ethernet connection.
I have a home router and have over 30 miners connected to it, 10 are on wifi, the rest are on ethernet cable across five TP-Link switches. Beside those, I have a wireless laptop, my phone, and a tablet that all connect to the wifi. I have an old acer laptop running lubuntu running as my media center on ethernet. All connect and use the internet fine. A few nights a week there are 2 to 4 others here with their phones and a tablet or two also using the wifi. The only wifi problems I have had have actually been the asic device/controller and not the home router. On top of all of that, I am using a ClearWire 4G modem to connect to the internet.