"Unable to join the network"

iPhones - updated with iOS7:

At home, I use a wireless gateway, that is WEP secured.

Before the update, the iPhones Wi-Fi would connect to the network automatically when in range.

Since the update, they will only connect after I change the gateway password.

After a period of time, they do not connect automatically.

When I "forget this network" and re-enter the current password, it returns an "unable to connect" error, until I change the password again.

This occurs with both of our iPhones, at home.

My iPhone does tend to connect normally to other secure networks I use regularly

I have other devices connected wirelessly at home that continue to operate normally, so I need to keep the original password.

There may be a setting I need to change in my gateway, or iPhones, but Comcast/Xfinity has not been able to help identify it and blames the iPhone for the failure to connect.

Any ideas?