I used to use my xbox via wireless connection. A few months ago I decided to start using the wired connection and it was working perfectly.
A few days ago I noticed I started having issues with connection to game servers, like Plants vs Zombies and Rayman. They were giving me an error saying my network wasn't setup.
This didn't make any sense, since I was connected to Xbox Live and could talk to friends and use online applications like Youtube or Internet Explorer.
When I went to Settings -> Network, it was showing I was connected via Wired Connection and that all Xbox live services were working, but when I tried to run network test or multiplayer test I was getting an error saying it couldn't connect to my DHCP server. Again, it didn't make any sense. Clearly I had an IP and was using the internet services.
Even more strange was the fact that the Detailed network test was successful, but that is where I started getting suspicious. It was giving me a download speed much slower than I was getting when I first tested my wired connection and I was getting some packet loss, which wasn't happening.
I then accessed my Linksys router to see what devices were connected and their IP and MAC addresses. I noticed that the Xbox didn't show as connected via LAN. It had an IP via wireless connection, so for sure my wired connection wasn't working.
After some more troubleshooting I finally discovered my powerline network adapter had lost the pairing with the other device and that's why it wasn't able to talk to the DHCP server. I paired the device again and everything started working fine.
To avoid this issue with other customers, Xbox should not use the wireless connection if that is not the one selected or at least explain that it is using both connections and be specific with which one is working and which one is not and what services are using one or the other. When I looked at the Network settings there was nothing telling me it was using wireless. It was only showing connected via Wired connection.
It would have saved me time troubleshooting.