Tuesday, 7 January 2014

3G router fun

Over the weekend I meant to play with Roll.app on my Chromebook. I didn’t quite get there as I started playing with my new TP-Link 3G router.

When we were in Sri Lanka in mid 2013 I noticed that a few of the smaller places we stayed in used TP-Link 3G routers for their internet connections. These are essentially a wireless access point into which you plug a compatible 3G or 4G dongle, and then share the mobile broadband connection between clients, without the need for multiple dongles etc.

So, given that our ADSL connection runs over some 1980’s overhead copper phone lines via a neighbour’s apple tree, and is prone to attenuation and drop outs, not to mention that the adsl service is grossly overloaded with too high a contention rate it might be time for a technology change, especially as given our monthly internet usage we can get a 4G bundle that would give us 150% of our monthly data usage for the same price we’re paying for a not very good ADSL service (ie we use between 8 and 10GB a month and can get 13GB of 4G for what we are paying for 50GB ADSL we’re not using fully).

Now I had a Huawei E173 modem that we used on our South Australia trip back in 2012. I checked the modem specs and yes the E173 was compatible with the MR3220.

So, I did the lego thing. Plugged the WAN port of the 3G router into the current ADSL network box, plugged the 3G modem into the port, connected a laptop via ethernet for the initial configuration and away we went.

Rather than have it was a standalone network, I was going to setup the 3G router to use the ADSL connection as the primary and the 3G as a backup, and then once everything was working nicely move the 3G over to being a standalone network.

The idea being to see how good the 3G service was in practice by testing it fully, but leaving us with a mostly working alternative in the meantime.

The WAN configuration bit worked well, and was reasonably fast. The only problem is that it there isn’t a way to set a a low DHCP timeout - given our unstable ADSL and the time it takes to come back it’s possible to have the TP-Link think there’s no working ADSL connection - if it rerequested an ip address every hour or so that would probably solve that problem.

However the real problem turned out to be the 3G connection. When I plugged the 3G dongle in I got a flashing blue light as I’d expect. Unfortunately, while the TP-link box allegedly knows about E173 modems it doesn’t recognise my Virgin Broadband E173 modem - which is a bit of a problem.
In fact it’s a bit more complex than that - for Australia it doesn’t ‘know’ about Virgin, only Telstra, Optus and Vodafone. I did try Optus as Virgin effectively resells the Optus service, but that didn’t work, even following Virgin’s modem setup guides.

Looking round the TP-Link support site they had some E173 config files for TurkCell and UK Vodafone - I downloaded them to see if they were readily hackable, but they turned out to be binary:

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Which was a problem. Googling didn’t help me - I did discover what the APN setting should be but without a modem configuration file I’m a bit stuck. I’ve a support ticket in with TP-Link at the moment …
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