That question doesn't make sense but you could restore the phone and upgrade to OS 3.1.3 then re-jailbreak and unlock.
If it's T-Mobile in the US, be aware that 3G won't work, Only Edge. Turn off 3G and it should work on Edge speeds.
I'm guessing by iPhone 2G you mean the original iPhone? What do you mean keep connected to the internet? Is it dropping your connection somehow? If it's the original iPhone, it doesn't have 3G.