I noticed in your lspci output that your Realtek network chipset isn't being detected completely and looked very similar to the comments in Bug 240470, particular this comment [1]. Please make sure that the BIOS on your system has the latest firmware upgrade applied.
[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/240470/comments/12 -- dhcp client can't receive an ip address https://bugs.launchpad.net/bugs/333481 You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to dhcp3 in ubuntu. -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs