ubuntu 11.04 beta Network

Ubuntu 11.04 has been out since the end of April. Why are you running the beta version? This would make sense if you had installed it when it was new, and then updated the beta to become the stable version.

I recommend you wipe the disk and reinstall from Ubuntu 11.04's official, stable installation media (obtainable at http://www.ubuntu.com/download/ubuntu/download or by torrent--which I recommend--at http://www.ubuntu.com/download/ubuntu/alternative-download#bt). You've just installed, so you haven't done much customization and it shouldn't be very cumbersome to do this, and sometimes there are edge issues that create problems updating development versions of an Ubuntu release to a point well after the start of the release.

Even if this does not fix your current problem (it might, or it might not), this may still help you to avoid other problems with this system in the future.

Please note that this advice is not usually necessary in cases where you installed a beta when it was new and updated it. If the beta was able to update fully without problems into the stable release version when the stable release version came out, then (on that specific installation on that specific machine) you shouldn't experience problems with that release version later due to it having originally been a beta.

If you follow this advice and you find that this networking problem still occurs, I recommend that you mark this question as Solved (you can do that at https://answers.launchpad.net/ubuntu/+question/166700) and post a new question (https://answers.launchpad.net/ubuntu/+source/gnome-nettool/+addquestion). Normally it is not advisable to post multiple questions about the same thing (and indeed, you should never do so unless all but one of them are marked Solved or Invalid, or perhaps in some cases Expired), but in this situation, there are really two issues at hand.

Or did you mean that you installed an Alpha of Ubuntu 11.10 (which is currently in Alpha 2 and will soon be in Alpha 2), rather than a Beta of Ubuntu 11.04 (which is currently a stable release, past any alphas or betas)?