WiPi – A RaspberryPi Hotspot To Go

tl;dr

A Raspberry Pi with a cellular HAT to act as a private internet access point and portable local network.

Taking paternity leave for the month of July to introduce our newborn to extended family introduced a lot of hurdles. With all going on in the world not many could be solved with some DIY tech. Being on the road for a month I thought it’d be rad to have a WiFi hotspot to connect to with a bit more configuration than just an iPhone.

In short the goals for the project were:

  • Portable WiFi Hotspot
  • Standalone internet connectivity
  • Bring our WiFi devices on the road and not have to setup or count on other folks / hotel / public WiFi access

Here’s the gist…

The Build

Hardware

  • Raspberry Pi 4B 2019
    • I chose a Raspberry Pi 4B for the base board for no other reason that I wanted to get an 4GB model for tinkering previously and had it to repurpose for this build.
  • Raspberry Pi 4G/LTE HAT Kit
    • Bundled from SixFab
      • Raspberry Pi 3G/4G & LTE Base HAT1
      • Quectel: EC25 Mini PCle 4G/LTE Module
      • 1LTE Full Band PCB Antenna – u.FL Plug – 100mm
      • 1LTE – GNSS Dual u.FL Antenna – 100mm

The Design

Over all pretty simple idea, a local wifi / lan with its own independent internet connection.

Few items of note here

  • I have never done anything with cellular providers / HATS etc and a Pi platform
  • I wrongly assumed most cameras have rtsp support out of box
  • I wrongly assumed modern applications are designed to be data conscious

Setting Up the Pi

OS

Flashed and installed Raspberry Pi OS Latest (formerly known as Raspbian)

Cellular HAT

SixFabHas Links to “Complete Documentation” on the Cellular Modem Kit‘s Page. I will say I was impressed that at the documentation SixFab Provides. Depending on your IoT cellular provider, Sixfab ships with a SIM from Twilio, you can follow the PPP/QMI tutorials respectively.

I was kind of like, “Wait thats it?” the Twilio SIM being QMI with some inherent trust didn’t need anything past the QMI tutorials Sixfab provided.

WiFi

RaspAP, billz/raspap-webgui

RaspAP lets you quickly get a WiFi access point up and running to share the connectivity of many popular Debian-based devices, including the Raspberry Pi. Our popular Quick installer creates a known-good default configuration that “just works” on all current Raspberry Pis with onboard wireless. A responsive interface gives you control over the relevant services and networking options. Advanced DHCP settings, OpenVPN client support, SSL, security audits, themes and multilingual options are included.

https://raspap.com/

Again, not a lot to say here, another great tool that “just works”.

Nebula

The Pi hosting the WiFi / Cellular connections is also enrolled in my nebula network, I talk a bit more about nebula in a previous post. This allows for this pi to reach other nodes that are also connected to the network, it does not treat the local lan as an extension of the nebula network. Once enrolled I was able to ping/ssh into the Pi via its cellular network, as well as reach any other resources as allowed on the nebula network. Very slick.

Extending WiFi via AC750

The TP-Link AC750 (TL-WR902AC) has built in functionality for various Wifi modes. Setting up to extend an existing SSID, then moving it away from the Pi’s location would allow for just that, an extended WiFi signal.

Assembly

Thoughts

All in all this was a fun project, not much use on the day to to day, but as a travel companion its a rad little setup. It was a fun project that will more than likely get dismantled into other projects!