I'm having an iPhone WiFi problem that's specific to the 3GS. 2G and 3G iPhones are not affected.

I have two different 802.11n access points here that cause the iPhone 3GS to "forget" the WPA key. It only seems to "forget" the key after connecting to another wifi network. In other words, network a (WPA2-PSK) works the first time you enter the key, then you go to network b (802.11g WEP). When you come back to network a, the iPhone 3GS seemingly forgot network a's WPA password. It prompts you to re-enter it. You diligently enter the password again, and it's rejected. Frustrated, you reboot the iPhone 3GS. When it's back up and operational, it connects to your WPA2-PSK network just fine with no prompts or additional input.

It's been this way since I got the 3GS. I've learned to live with it by rebooting the 3GS daily when I get to work in the morning. Now there is another 3GS here, so it's probably time to get to the bottom of this.

At first, I thought my cheap AP of choice was just being a pain. Last week, I sniffed-out a deal on another cheap AP, and it's doing the exact same thing.

This problem appears to be a 3GS issue, though I can't blame Apple entirely because my taste in networking equipment is clearly low-end.

I've searched numerous Apple boards and can't locate anyone with the exact same problem as me. However, there are numerous complaints about wifi and the 3GS. I was hoping that 3.1 would have fixed this, but it obviously didn't. It must be some hardware bug since the 2G and 3G models here work just fine with 3.x.

Before I blindly buy more hardware, is there an AP that will definitely work with the 3GS using WPA2-PSK in the scenario I described in the 2nd paragraph? I assume Apple hardware will work, but as far as I'm aware Airport Base Stations are not strictly access points. They seem to be routers and Apple's website isn't clear if it's able to be used as an access point. Annoyingly, Airport Base Stations seem to have a client limit. This is almost reason-enough to not consider them.

I have to buy 2-3 APs to cover the area, so price is a factor. I realize I'm trying to get away with something by getting sub-$50 hardware. Hopefully, we can get a decent device for less than $100 per AP. Am I nuts?

I am also open to other security schemes, but I will admit I'm not well-versed in this area. WPA2-PSK with AES encryption is the most robust security I'm able to set up (and understand). The new Zyxel APs don't support WPA2 Enterprise, but the Trendnets apparently do. I don't know much about WPA Enterprise or how to set the key and/or other parameters. Is it just a matter of selecting an incredibly long key, or is there more to it? A quick google search isn't really explaining the difference between regular WPA and Enterprise.