I recently purchased a Steam Deck because I wanted to be able to kill some time when I had to do some waiting i.e. waiting in the car for my wife, waiting for my flight at the airport, etc. So, a full on console didn't work for me since I would need to physically be at home and be able to dedicate extra time to play games. I needed a hand-held gaming device and Steam Deck seemed to fit me well. Not only was this a gaming device but a full Linux PC! That meant that if, one day, I got tired of playing games, I could always use the Deck for something else. That's why I didn't really want to buy a Nintendo Switch since I would only be able to run games on it, worse yet, only Nintendo games, which would be too limited for me. I also wanted to catch up on some good games that I missed out on.

It turned out to be a good choice. Steam had a lot of titles I wanted to catch up on, and the Deck being a Linux PC, I was also able to play retro games that I missed out on by installing EmuDeck. It also had great community support online.

Everything was great until I realized one big caveat: it only had WiFi. This meant that I would only be able to play this at home for the most part. Technically, I COULD play in offline mode, but with all these games being connected to the cloud server, it was just inconvenient. In fact, it sort of defeated the whole purpose of getting a hand-held device over a console like PS5 or Xbox.

And then i remembered that the Deck was really just a Linux PC which meant that I could just connect the LEMBAS modem and enable cellular data on my own! I tried looking on online forums (reddit, quora, etc.) to see if there was already an established way of connecting the Deck to LTE, but I was not able to find any "official" solution. So, I thought might as well upload my method and share 😄. So, here is one "convenient" way of enabling LTE on the Steam Deck and completely going mobile. Hope you enjoy!

Check out this project and more on www.amikers.com!

Supplies

Absolutely Required:

Steam Deck (I got the 64GB version) Link
LEMBAS USB Modem Digi-Key / Mouser / Arrow / Avnet
USB-A to USB-C Adaptor Link

Nice-to-have:

Steam Deck Dock Link
Monitor w/ HDMI cable
Keyboard and Mouse
3D printed modem holder
Steam Deck Case Link

Just in case you want my 3D file for the modem holder, I am attaching it here. One is a .gcode file, which is the format needed to print on Creality Ender 3 3D printer. The other is a general .stl file which you should be able to use to print on other 3D printers.

Step 1: Purchase Data Plan

What is nice about using the LEMBAS is that SIM card comes built-in. The official data plan provider for the LEMBAS is Pod Group. In my opinion, their monthly rate is very competitive. Check it out for yourself!

Go to https://lembas.luner.io.
Create an account or log in. You will need to enter your credit card information during the account creation process.
After successfully creating an account or logging in, click on "Provision SIM" on the top right side of the page.
Enter the SIM number which is printed on the back of the device (3rd line from the top indicated as "SIM No.").
Choose data plan.
Review and confirm order to activate data plan.

This data activation platform is pretty straight forward in terms of what you can do, so click around and get familiar.

Your card will be automatically recharged on the 18th of every month, so if you don't want to renew, make sure to cancel plan. You can do this by clicking on the 3 vertical dots on the right side of the dashboard and clicking on "Cancel Plan". A pop-up will show asking to confirm. I'd advise to click on "Confirm and Queue Cancelling Plan" because this option will let you use your data plan until the next recharge date (the 18th). If you click on "Confirm and Instantly Cancel Plan", this will instantly disable your LTE connectivity as soon as you are done clicking.

If you ran out of data for the month, then you can always add more data by clicking on "Add Bolt-on". This plan will NOT be automatically renewed. Your card will be charged only that one time you opt-in for extra data. Just remember to add bolt-on data ONLY when you run out of data for the month because bolt-on data will overwrite your current plan for the month regardless of whether you have data left or not in your original plan. The platform does give you a warning message about this.

NOTE: The current data rate will be charged every 18th of the month, and there is NO prorating or rollover. This means that if you purchased a data plan on the 17th of the month, then you will be recharged the full amount the next day on the 18th which will last until the 18th of the next month. So, make sure you choose wisely. If it happens to be the 18th of the month when you are trying to purchase a data plan, then you can choose any data rate you'd like to use until the 18th of next month. But if it happens to be near the 18th of the month already, I'd advise to choose a data plan that you know you will use for the remaining days until the 18th (e.g. 3 days if you are activating data plan on the 15th).

Step 2: Setting Up LTE on Steam Deck

The LEMBAS device is not naturally compatible with the Steam Deck, so you will need to ignore the set-up instructions in the instructions manual that comes with the device. The only instruction that applies to this is the data plan set-up instructions. You can follow that portion of the instructions manual, which is basically the same as what I wrote in Step 1 above.

Follow the steps below:

Power up Steam Deck.
Switch to Desktop Mode by pressing on the "STEAM" button on the left corner of the Deck, then "Power", then "Switch to Desktop".
Make sure you are connected to WiFi.
Open Konsole. If you cannot find it, click on Application Launcher at the bottom left corner of the screen (Start button equivalent on Windows), and type "konsole" in the search bar.
Clone the git repository:

git clone https://github.com/jinzohh/steam_deck_cellular.git

Make sure to be in the "/home/deck" directory which is the default directory when you open Konsole.

NOTE: If you don't have a separate keyboard and mouse, you can open the GUI keyboard by holding STEAM button and pressing X (hold STEAM + X). This will pop up a GUI keyboard on screen.

Disable WiFi. Click on the WiFi icon at bottom right and then uncheck the WiFi icon.
Connect the LEMBAS device to the USB-C port of the Deck. If using the USB cable that comes with the LEMBAS, use the USB-A to USB-C adaptor indicated in the "Supplies" section of this tutorial.
Going back to Konsole, change directory into "steam_deck_cellular" folder:

cd steam_deck_cellular

Then type:

bash activate_cell.sh

Enter your Deck sudo password when prompted to do so.
Reboot the system when prompted to do so.

After reboot, the LEMBAS will work as plug-and-play. Simply unplug the USB cable to deactivate and plug in to activate LTE connectivity.

NOTE: In the instructions manual of the LEMBAS, it does indicate to first turn off power by holding the power button for 2 seconds. But this button isn't easily accessible and can only be pressed with a paper clip or a SIM ejector pin, If you can, then maybe it would be best to power down this way before unplugging, but I didn't have any issue just unplugging the cable. I will leave this up to you.

And that's it!

So, next time you'd like to play on the Steam Deck when you are outside without WiFi, just plug in the LEMBAS device to stay connected!

Cheers!