Incorrect Password and cannot connect to my extender...

I have had the NetGear WN3500RP Dual Band Extender for several months now and it has worked great! Originally I had a successful installation, however, 2 weeks ago I got a new upgraded router (AT&T's residential gateway for u-verse) and I had to reset my extender and set it back up (our network name and password changed). I set it up and both the 2G and 5G networks are listed but when I put the password in it says "Incorrect password for XXX" for both networks. I have all 3 (my main network and both extenders) set up as WEP with same name, except for the ext, and password as instructed. I cannot figure out what the problem is and have spent countless hours trying to figure it out. The only thing I can figure out is I have noticed that when the screen that comes up to rename your network and change your security settings (if you'd like) comes up it's says (after hitting continue) that in about 2 minutes another screen will come up - you know the "one step away from completing installation screen" where you are to check your settings and make sure they are correct, then "After you are successfully connected your wireless computer/device to your extender network, go back to the extender Genie screen and check the option "My wireless devices are connected to the Extender network". I don't get those last two screens. I haven't been able to log back into mywifiext.net either to try and finish it. So to make a long story short - I think I am 90% connected (the green light is on solid my extender for the network) but I cannot connect to it because it is not recognizing my password (i.e.: passphrase). HELP!!! This is taking - wasting - too much valuable time! Oh, I have apple products, if that matters. Shouldn't as I was connected before. Thank you in advance for any assistance or guidance.