Comment 2 for bug 518448

I have the same problem with my two USB 3G devices: a Huawei E169 and a Huawei E160E on Ubuntu 10.04 (Lucid Lynx) with latest updates as of September 8th, 2010. Same issue with two different mobile broadband providers in Australia that I use (Internode and Virgin).

So it's not particular to your E172. I think the bug is just to do with the woeful inadequacy of Network Manager. It doesn't have reliable "persist" features. It regularly gets its nickers in a twist and just refuses to keep trying a connection, it just spits the dummy and gives up - permanently until the user manually clicks connect. Silly.

There really needs to be some decent and reliable "persist" options with NM.

Windows is way better in this regard, by default Windows always tries to reconnect and is noticeably more reliable at keeping connections up, no matter if your DHCP server is temporarily unavailable or your signal is out for a bit, or whatever, it keeps trying.