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MU300 Linux wiki

In one sentence: this project puts a real Linux system (Ubuntu or OpenWrt) on the ZTE F50 / MU300 and the ZTE U30 Air pocket 5G hotspots, next to Android, so the little box becomes a Linux router and server with its own 5G modem.

The simple version

Your hotspot is a tiny computer. Out of the box it runs Android, hidden behind a web page, and does one job: share mobile internet. This project adds a second system, Linux, in a part of the storage Android does not use. When the device starts, it starts Linux. If Linux ever fails to start a few times in a row, the device quietly goes back to Android on its own. Android is never removed, and one command brings it back for good.

Think of it as a Raspberry Pi that already has a 5G modem, a Wi-Fi access point and 32 GB of storage inside.

Where to start

If you want to…	Read
understand what you need and install it	Installation
pick between Ubuntu, OpenWrt and OpenWrt with the control panel	Choosing a System
pick a kernel (5.4, 6.18 or 7.2)	Kernels
get mobile data working, set an APN	Mobile Data and APN
change the hotspot, or join another Wi-Fi	Wi-Fi Hotspot and Client
read and send text messages	SMS
route everything through a VPN	VPN
use the web control panel	Control Panel (LuCI)
update, or roll an update back	Updating
go back to Android, or remove Linux	Going Back to Android
fix something	Troubleshooting and FAQ
look up a word	Glossary
know how the hardware behaves	Hardware Notes
build it yourself or help out	Building from Source, Contributing

There is also an illustrated website with the same information for beginners, in English, Turkish and Chinese: https://kaandikec.com/mu300-linux/

Supported devices

	ZTE F50 / MU300	ZTE U30 Air
Chip	Unisoc T760 (UMS9620), board ums9620_2h10_feimao	the same
Power	USB only	battery (4050 mAh)
USB network address	192.168.77.1	192.168.78.1
SD card	yes: Linux can live on the card	no card slot

The installer recognises which device it is talking to. The U30 Pro is a different chip (UMS9632) and is not supported. More in Hardware Notes.

What you get, and what you lose (spoiler: nothing)

You get: Ubuntu 24.04 or 26.04 LTS, or OpenWrt 25.12 (plain or with a control panel for the modem); three kernels to choose from; 5G/LTE internet shared over Wi-Fi and USB; SSH, and adb over USB if you turn it on; Bluetooth; SMS and USSD; an optional VPN module; a web panel on Ubuntu too (Cockpit with an MU300 page, optional); a raspi-config-like menu called mu300-toolkit; automatic fallback to Android; updates on the device.

New in v2026.10.23

The release of 2026-10-23 (a prerelease first, promoted once a board has run it). What it changes, and where to read on:

• The modem on mainline after a Magisk install (issues #127, #170): Android files the installer imported could end up readable by root only, and the modem's processor was then never loaded. The installers write them with the right modes now, and every boot repairs an import that is already there. Troubleshooting
• A thermal zone on 6.18 and 7.2: the board's temperature is a kernel thermal zone (mu300_thermal), and thermal-guard hands over to it. Kernels
• SMS arrive at once on OpenWrt: the modem delivers a message as it comes in (+CMT) instead of waiting for the next poll, and forwarding to a webhook can have a body of your own (issue #171). SMS
• The panel shows the SIM's own number, shows a carrier name the modem sends as hex as text (issue #174), hides a SIM slot the board does not have, and a band or cell lock reset is checked after it is made.
• The VPN page says why a config was refused instead of "profile not added", and its check works. The engines' own fixes are in VPN module v2.0.1 (mu300-extra install vpn again): sing-box, mihomo and dae find their server on carriers that only let DNS through to their own resolvers, mihomo configs with GEOSITE/GEOIP rules start (the geodata comes with the extra), dae stays up on 6.18 and 7.2, and switching to a profile that cannot run leaves the working tunnel alone. VPN
• Installers: a stalled write to the SD card or the internal storage is noticed and reported, and the boot image is read back after it is written. Installation
• Kernels: 5.4 rebuilt with NFT_QUEUE; 6.18.56 and 7.2.10 with the thermal module. Kernels

New in v2026.10.22

The release of 2026-10-22 (a prerelease first, promoted once a board has run it). Fixes again. What it changes, and where to read on:

• Sending an SMS no longer fails with SMS FAILED: CODE:600 on networks that refused every submission (China Broadnet; issue #176): a send is now one AT transaction, with nothing else getting at the modem between the setup and the submission, and the SMSC is written back to the modem unchanged before each one; on OpenWrt (mu300-sms and the panel) and on Ubuntu (sms). SMS, Troubleshooting
• The panel's SMS page keeps its send result: a slow send used to be killed with the request after 30 s (sms_send - killed in the operations log). The send now runs in the background and the page follows it, also after a reload. Troubleshooting
• No more mmc1 register dumps on the F50 on 6.18 and 7.2: the empty SD slot has real card detect now (the EIC controller's six banks are mapped), so nothing polls it any more (issue #181). Troubleshooting, Kernels
• Magisk zips: known passwords. A system the zip installs gets the images' own: Ubuntu's user ubuntu has the password ubuntu, OpenWrt's root has none until you set one; MU300_PASSWORD still sets one of your own. No random passwords any more, and the password note holds no secret (issue #167). Installation
• No VPN section without the VPN module: LuCI's VPN menu, the Cockpit page's VPN tab and the toolkit's VPN item are there only once mu300-extra install vpn has run. VPN
• Kernels: 5.4 unchanged; 6.18.56 and 7.2.10 rebuilt with the card-detect fix. Kernels

New in v2026.10.21

The release of 2026-10-21 (a prerelease first, promoted once a board has run it). Mostly fixes. What it changes, and where to read on:

• F50: the internal SIM can be selected instead of the card in the slot: mu300-sim select internal (or the SIM source field of the wan interface in LuCI), with that card's own APN. It takes effect at the next boot, the external card stays the default, and nothing is written to the modem or the SIM. docs/SIM-SELECTION.md
• Kernel 5.4 no longer panics when a network namespace goes away (Docker containers, sandboxes; issue #103). Troubleshooting
• The Wi-Fi driver can be unloaded on 6.18 and 7.2: rmmod sprd_wlan_combo used to crash the device (issue #146). Troubleshooting
• Quieter logs: the Wi-Fi driver's routine lines (sc2355_dump_survey, bssid not found, data len is...) are no longer errors in dmesg and logread, on every kernel (issue #140). Troubleshooting
• mu300-update runs one at a time: a second run started meanwhile is refused and names the first one's pid. Updating
• Kernels: 5.4 rebuilt with the two fixes above; 6.18.56 and 7.2.10 with rebuilt modules. Kernels

New in v2026.10.20

The release of 2026-10-20 (a prerelease first, promoted once a board has run it). What it adds, and where to read on:

• Updates keep the packages you installed (apk add, apt install): they come back at the first boot, with their settings and their services' state; the panel shows it under System > Packages after an update. Updating
• The control panel gets a VPN section (Overview, Profiles, Subscriptions, Engines, Settings, Logs), System > Terminal (a root shell in the browser, LAN only), Wi-Fi clients with their speeds on the home page, the Power page's reasons in your language, and it no longer freezes when an AT command gets stuck: on OpenWrt an AT command now takes 0.13 s instead of a second. Control Panel (LuCI)
• A web panel for Ubuntu: Cockpit with an MU300 page, as the panel extra. Control Panel (LuCI)
• VPN module v2.0.0: a core plus engine extras (vpn-xray, vpn-singbox, vpn-mihomo, vpn-dae), subscriptions, and an IPv6 guard so nothing leaks beside a tunnel that carries no IPv6. VPN
• Kernels 6.18.56 and 7.2.10, with BTF and the eBPF hooks dae needs. Kernels
• U30 Air: a charge limit of 0-100 % (mu300-power charge-limit N), and faster charging on Type-C ports that offer 1.5 or 3 A (mainline kernels). Hardware Notes
• The hotspot never lands on a DFS channel any more (it used to fail to start there). Wi-Fi Hotspot and Client
• adb to Linux over USB (mu300-usb adb on; off by default, your computer's key must be authorised). Installation
• The installers copy the boot chain of Android's slot to the Linux slot after an Android update (issue #86). Installation
• Hardening: the Android modem daemons run under their own account (mu300vnd) and nothing in /dev belongs to the login user any more; sms delete sends only a message index to the modem. Hardware Notes, SMS

You lose: nothing that was there. Android on these boxes has no screen, no speaker and no HDMI either; all Linux takes is your last excuse for not having a 5G Linux server in your pocket. Installing it costs you nothing; not trying it costs you the server.

• Android stays. Only one of the two runs at a time, and a reboot switches between them.
• The hardware stays what it is, under either system: no screen output (HDMI over USB-C does not work), no speaker or microphone (voice calls with audio are work in progress), about 1.4 GB of the 2 GB RAM usable, because the modem keeps the rest.

A hobby project, at your own risk

This is an experimental hobby project. It is not a product, it has no support line and it comes with no warranty of any kind. Rooting and unlocking the device are not part of this project and are done at your own risk. Writing to a phone-class device can leave it unusable; keep a backup and do not install on a device you cannot afford to lose. Nothing here is endorsed by ZTE, Unisoc or any operator. Read the full notice in the README.

Links

• Source code and README: https://github.com/dikeckaan/mu300-linux
• Releases (prebuilt images): https://github.com/dikeckaan/mu300-linux/releases
• VPN module: https://github.com/dikeckaan/mu300-linux-vpn
• Deep technical notes: docs/FINDINGS.md
• Issues: https://github.com/dikeckaan/mu300-linux/issues