I have an iPhone 3GS on 3.0.1 (jailbroken with redsn0w and unlocked with ultrasn0w).

I live in a house with four Macs and a Time Capsule. Once the iPhone has joined the Time Capsule's wifi network, no Mac not already on the network can access the internet. Any Mac attempted to access the internet will not get an IP address.

I had the same issue with my previous iPhone 3G (also jailbroken with redsn0w and unlocked with ultrasn0w).

I can't pin down whether it's the jailbreak or the unlock causing the problem. I have tried to uninstall ultrasn0w but then the iPhone is just completely unable to join the authorised cellular network (o2).

I actually only need the phone to be unlocked when I'm traveling abroad (just got back from Switzerland where the data I used would have cost 204 roaming but in fact cost me 12 with a Swisscom SIM). So I would prefer to restore the phone to 3.0.1. But I can't as I don't have details saved on Saurik's server and there is no tool for the purplra1nyday file I have.

Any ideas how to solve the network issue?