I have several Acer Aspire One laptops that are acting as data loggers. I installed Ubuntu 8.10 on all of them. The hope was to use them to log the data and then relay it back to a local server. We wrote some software that does that is it works wonderfully when connected to the internet.

The cellular modems, when they are connected, work great. The problem occurs when the lease on the IP address is up. From my experience a new one isn't assigned or it is assigned and the computer won't recognize it. When this happens the modem can be unplugged from the USB socket then reinserted and generally everything is fine, however this is unexeceptable for a remote unmanned facility.

This was an unexpected problem and I came up with a crappy work around. I just pinged sites on a regular basis and if a reply wasn't received the machine rebooted. This was quick and dirty.

I tried stopping and restarting networking. This didn't work, I believe the modem need to have the power cycled. I tried to cycle the power from internally by it won't work on these computers. I even cut into the usb cable and switched the power to the modem with an external relay. This works except that I can't get the network manager auto connect back up.

Any help or advice is appreciated. I have a lot more information if it is needed.

You may need to remove network manager and start managing ppp link directly.
This way you will be able to control various aspects of ppp link and force pppd to bring the link up once it is down.

Network Manager may not be a suitable solution because it lacks the ability of maintaining the link persistently. It is not trivial to manage it outside of GUI and/or create scripts to do this. With pppd it is extremely easy.

In case the modems get stuck, this becomes non-trivial. I guess the fastest way to check that is to wait until link drops, then try issuing AT commands, say ATD*99***1#. If you succeed with CONNECTing, then this is definitely Network Manager problem.

Uninstall "Network Manager" - it's not good.
Install wicd instead

And welcome to LQ!

i have a question. i think Wicd is much better and faster to connect to wi-fi than the default Ubuntu Network Manager (i'm using Ubuntu 9.04).

but is there some sort of plug-in or add-on (hopefully that could be activated through point and click in Synpatic) so Wicd could go online using 3g/ WWAN on my Nokia phone?

on the default Network Manager, all i do is plug my Nokia phone to the computer with a USB cable, and it configures it in seconds and i could go online.

i don't use 3g all that often, just at times when there's no wi-fi around. but it's good to have that option in Wicd.

if there's no such add-on, is there another separate 3g "dialer" program that's easy to install and use on Ubuntu? thanks.