These days, we’re blessed with cellular data networks that span great swathes of the Earth. By and large, they’re used to watch TV shows and argue with strangers online. However, they’re also a great tool to use to interact with hardware in remote locations, particularly mobile ones where a wired connection is impractical.
In this series, we’re taking a look at tips and tricks for doing remote cellular admin the right way. First things first, you’ll need a data connection – so let’s look at choosing a modem.
When shopping around for cellular data modems, it can be difficult to wade through the variety of options out there and find something fit for purpose. Modems in this space are often marketed for very specific use cases; at the consumer level, many are designed to be a no-fuss home broadband solution, while in the commercial space, they’re aimed primarily to provide free WiFi for restaurants and cafes. For use in remote admin, the presence of certain features can be critical, so it pays to do your research before spending your hard earned money. We’ve laid out some of the common options below.
Many telecommunications providers around the world sell cheap USB dongles for connecting to the Internet, with these first becoming popular with the rise of 3G. They’re somewhat less common now in the 5G era, with the market shifting more towards WiFi-enabled devices that share internet among several users. These devices can often be had for under $50, and used on prepaid and contract data plans.
These devices are often the first stop for the budding enthusiast building a project that needs remote admin over the cellular network. However, they come with certain caveats that can make them less attractive for this use. Aimed at home users, they are often heavily locked down with firmware that provides minimal configuration options. They’re generally unable to be set up for port forwarding, even if you can convince your telco to give you a real IP instead of carrier-grade NAT. Worse, many appear to the host computer as a router themselves, adding another layer of NAT that can further complicate things. Perhaps most frustratingly, with these telco-delivered modems, the model number printed on the box is often not a great guide as to what you’re getting.
A perfect example is the Huawei E8327. This comes in a huge number of sub-models, with various versions of the modem operating in different routing modes, on different bands, and some even omitting major features like external antenna connectors. Often, it’s impossible to know exactly what features the device has until you open the box and strip the cover off, at which point you’re unable to return the device for your money back.
All is not lost, however. The use of VPNs can help get around NAT issues, and for the more adventurous, some models even have custom firmware available on the deeper, darker forums on the web. For the truly cash strapped, they’re a viable option for those willing to deal with the inevitable headaches. There are generally some modems that stand out over others in this space for configurability and ease of use. This writer has had great success with a now-aging Sierra Aircard 320U, while others have found luck with the Huawei E3372-607. As per earlier warnings though, you don’t want to accidentally end up with an E3372-608 – thar be dragons.
Commercial and Industrial Hardware
For those who don’t wish to muck around, more serious hardware is naturally available. Commercial and industrial grade equipment naturally comes at a higher cost, but is usually fully unlocked to configure as you please. This also avoids the pain of SIM locks, allowing you to use any network you so desire.
At the lower end, products like the Sixfab LTE Base Hat provide a straightforward cellular data connection with a minimum of fuss. Depending on the exact companion parts chosen, it can be set up to suit a variety of regions around the world and optimized for low power consumption or high throughput. At the higher end, you can have just about any set of features you so desire, as long as your pocket book is large enough.
Dual SIM options bring the benefit of fail-over capability to keep your remote system online when signal is poor, while others pack in multiple LAN ports to support many systems. There are even devices on the market specially designed to remotely monitor serial terminal hardware over 4G/LTE with a minimum of fuss. Most devices at this level also feature support for VPNs built in, making it easier to access your remote machines as if they’re on a local network.
At this level, you’ll usually have the benefit of being able to talk to a dealer or retailer about exactly what features you need before you buy. This is in stark contrast to trawling obscure forums for information on consumer cards, and for any serious engineering purposes where time is money, this is the way to go. Such hardware is (usually) better supported by the manufacturer, too, as it’s expected you’ll be using it in a situation that requires high uptime and good reliability.
In the end, the hardware you decide to use will come down to your use case. If you’re working on a serious project that needs to work, choosing the proper industrial hardware will be the way to go. If you’re having fun with a remote build as a hacker or maker, saving a few bucks might make up for a little hassle in getting things up and running. Of course, the Hackaday community is full of people who have been there and built that, so be sure to sound off in the comments with your best recommendations for picking the right cellular modem. Happy hacking!