I'm having a hard time getting online to play with friends or download new songs with my Xbox 360.
For some general tips regarding online connections, read on:
If you are having issues getting online or using online game features, please check out the topics in this sticky before you post.
Connection Issues on Xbox 360
The Xbox Live service requires that UDP ports 88 and 3074 and TCP port 3074 be available. Make sure your router and ISP are both allowing use of these ports. If you are using a router, make sure it is on the list of Xbox Live-compatible routers.
How to Get the Downloadable Songs on Xbox 360
To get downloadable songs on your Xbox 360, simply go to the Marketplace blade, choose Games and then Rock Band. All available content will be listed.
How to Access Purchased Songs on Xbox 360
Purchased songs will be added to your playlist in the appropriate sections and will also come up during mystery sets. If you cannot access your downloaded songs, you may need to make sure your console is setup correctly to do so. Visit EA's knowledgebase for tips on how to do this: http://support.ea.com/app/home.
If you've followed the suggestions here and are still having issues, then you are likely experiencing an issue concerning your router's firewall and your NAT level settings. On your console, visit the settings/network settings menu to determine your setting. The NAT option will evaluate to "Open/Type 1", "Moderate/Type 2", or "Strict/Type 3". If your settings do not indicate an "Open" NAT (i.e. both are "Moderate"/"Strict" or Type 2/Type 3), then NAT is preventing you from connecting.
One suggestion would be to try connecting your console directly to the internet, taking the router/firewall out of the picture. This is only a suggestion – and it is highly recommended that you look into all risks invovled with bypassing the firewall on your system to connect.
You may want to contact consumer support for the system you're playing on for further suggestions and help troubleshooting your connection.