Turning an old Pixel 3a XL into a fully offline, battery-powered web server with postmarketOS & Lighttpd

[muttmutt@lemmy.world]

I had an old Google Pixel 3a XL sitting around and decided to see if it could handle running as a fully offline, self-contained web server.

I flashed postmarketOS 26.06 (headless Alpine Linux base) to it and set up a portable media node that broadcasts its own Wi-Fi AP, serves static pages, and streams video over a captive portal - no cell data or upstream internet needed.

Quick Hardware/Tech Stack Breakdown:

• Device: Google Pixel 3a XL (2019)
• OS: postmarketOS 26.06 (CLI base with OpenRC)
• Networking/AP: hostapd for the AP, dnsmasq for DHCP & wildcard DNS routing
• Firewall: nftables redirecting port 80 requests to trigger the captive portal popup automatically
• Web Server: Lighttpd handling HTTP requests and MP4 video range requests

Performance & Power Draw: Under a test load streaming 720p video to 4 concurrent devices, total CPU usage averaged around 5% (load avg 0.51). Power draw stayed around ~2.4W off the internal battery, with temps holding steady at 54°C.

Why build this? Mainly as an offline entertainment and information node. I run a non-profit foundation providing SCUBA training to young survivors of childhood abuse, and having a tiny, battery-powered web node lets us provide offline information and videos to people while traveling. I will also be able to use it to provide training videos if I am teaching in a location that does not have internet access available.

I wrote up a complete overview covering the setup, and performance metrics if anyone wants to replicate it or build something similar. Over the coming weeks I will be posting configs and some other information to Github with a link from my site.

https://www.muttmutt.us/geeky-stuff/portable-web-server-on-an-android-phone-for-offline-access/

Happy to answer any questions about postmarketOS setup or the networking config!