I believe that WPA was the original WPA standard, and WPA2 was an improved version of it. Some network cards can’t connect to WPA2 networks. From the Wikipedia page on WPA:
The later WPA2 certification mark indicates compliance with the full IEEE 802.11i standard. This advanced protocol will not work with some older network cards.
The Wikipedia article cites a white paper from the Wi-Fi Alliance:
WPA is both forward and backward-compatible and is designed to run on existing Wi-Fi devices as a software download.
In a nutshell, a WPA/WPA2 network will any network card that supports WPA or WPA2 to connect to it; whereas a WPA2 only network locks out network cards that only support the newer standard. I don’t think there’s any meaningful difference in the security.
FWIW, I’ve used WPA2 Personal on my Airport Extreme since I bought it, and no device has ever had problems connecting.
Confession: I initially misread the question as being about the difference between Personal and Enterprise, and wrote this. Although not directly answering the question, I include it for interest.
“Personal” and “Enterprise” just refer to the two flavours of WPA and WPA2. From the Wi-fi Alliance’s page on WPA2:
WPA2 can be enabled in two versions - WPA2 Personal and WPA2 Enterprise. WPA2 - Personal protects unauthorized network access by utilizing a set-up password. WPA2 - Enterprise verifies network users through a server. WPA2 is backward compatible with WPA.
I believe that WPA and WPA2 both come in these two flavours, hence the either/or. Personal is more suitable for a home network, but it’s less secure than enterprise. Enterprise connects to a “RADIUS server” for authentication. I don’t know what that is, but it sounds clever and secure.
I’d guess that a device connecting to your Time Capsule just sees a request for a WPA2 password, hence why it doesn’t ask you for a WPA2 Personal password.
Changing network parameters like channel assignments might cause more harm than good, especially on the long turm. You may end up in having to analyse strange issues...
Use a professionnal tool to analyse your wireless environment first:
iStumbler.
If you want a professionnal help, please put a copy of a screen capture with this tool. Make this environmental measure at a point which is as near as possible from the point you want to communicate with your Time Capsule usually.
Take care to make this measure at the hour you witness your slow network throughput.
Sort the output along decreasing signal level (Level column).
Take care to hide private information from this screen capture.
If you have a real environmental problem (which a real and highly frequent situation), fix it.
Else, bring back your Time Capsule to your Apple reseller. Most probably an antenna cable was not correctly fixed inside, and a move made it unplug.
Best Answer
Uninstall both would be my recommendation.