user780: I installed Bitcoin QT yesterday and it was very slow to connect to the network. It didn't actually get there for over an hour.
Today I opened it again and it won't connect to the network at all. Any ideas why?
I'm running a Macbook Air with all software updated.

user154: You can download the blockchain and hence skip this long lasting initialization step.

user85: You are probably still not synchronized to the network. When the client first starts up, it doesn't trust anything or anyone. So it has to validate every single thing the Bitcoin network has ever done in order to understand what coins are valid now. This can take 12 hours or so, depending on your connection speed and CPU speed.

user323: You should get the best results if you port forward port 8333 to your laptop. It is also advised to leave your computer on for a long time the first time you connect to the network, as it has about 1GB of data to download and check. After that the operation should be easier.

780: <p>I installed Bitcoin QT yesterday and it was very slow to connect to the network. It didn't actually get there for over an hour.</p>

<p>Today I opened it again and it won't connect to the network at all. Any ideas why?</p>

<p>I'm running a Macbook Air with all software updated.</p>
 154: <p>You can <a href="https://bitcoin.stackexchange.com/a/802/154">download the blockchain</a> and hence skip this long lasting initialization step.</p>
 85: <p>You are probably still not synchronized to the network. When the client first starts up, it doesn't trust anything or anyone. So it has to validate every single thing the Bitcoin network has ever done in order to understand what coins are valid now. This can take 12 hours or so, depending on your connection speed and CPU speed.</p>
 323: <p>You should get the best results if you port forward port 8333 to your laptop. It is also advised to leave your computer on for a long time the first time you connect to the network, as it has about 1GB of data to download and check. After that the operation should be easier.</p>
