About this post. Written by Rocket Routers about our own firmware — we know it better than anyone because we built it. We use AI assistance (Claude, by Anthropic) to help draft and research content — we review everything before it goes live. Firmware specifications and availability are correct as of the date of this post.
Why custom firmware at all?
Every Rocket Router ships on hardware that already runs OpenWrt — the most capable open-source router operating system in the world. The major manufacturers — TP-Link, ASUS, Netgear — take this same hardware and ship it with locked-down firmware that hides most of its capability. You get a nice interface and a fraction of what the hardware can actually do.
We go the other way. Our firmware is built from the OpenWrt source, configured specifically for the hardware we sell, and extended with our own scripts that handle things like cellular modem detection, automatic failover setup, port configuration, mesh networking, and encryption tools. Every setting that matters is configured correctly on first boot — you do not need to know what UCI is, what mwan3 does, or how to configure a WireGuard interface. It just works.
But because it is built on OpenWrt, if you do know what you are doing, you have full access to everything underneath. SSH in, use UCI, install packages, do whatever you need. Nothing is hidden from you.
The four firmware variants
Cell-only. Plug in, SIM in, done.
Firmware A is the starting point — and for most customers, the only firmware they will ever need. It is designed around a single principle: if you have a SIM card, you have internet. No fibre required. No engineer visit. No configuration.
On first boot, Firmware A detects how many Quectel 5G modems are present in the router. If it finds one, it configures single-modem cell internet with automatic APN detection and keeps mwan3 (our failover engine) dormant — there is nothing to fail over to, so there is no point running it. If it finds two modems (the Supreme variant), it automatically configures dual-modem load balancing so both SIM connections are used simultaneously.
A1 — single modem. One SIM, one connection. Typical speeds 30–150 Mbps depending on signal and carrier. Ideal for a home, a small office, or anywhere you need reliable internet without fibre.
A2 (Supreme) — dual modem. Two SIMs, automatically load balanced. Put them on different carriers for both extra speed and carrier redundancy. Coming when dual-modem hardware is available.
Fibre primary. Cell failover. Never goes down.
Firmware B is for customers who have fibre broadband but cannot afford for it to go down. The SFP+ port connects to your fibre ONT or incoming ethernet. Cell is the backup — it sits ready but dormant, and the moment fibre drops, mwan3 switches traffic to cellular automatically. When fibre recovers, it switches back. Your devices never notice.
This is the setup that businesses used to pay managed service providers hundreds of pounds a month for. With Firmware B it is built into the router on first boot — detect fibre, detect cell modem, configure failover, done.
B1 — single cell modem. Fibre primary, one SIM as backup. The right setup for most businesses with fibre.
B2 (Supreme) — dual cell modem. Fibre primary, two SIMs as backup load balanced across two carriers. Even if one carrier has an outage during a fibre failure, the other carries on. Genuine triple redundancy.
SFP+ as LAN trunk. Cell WAN. Building-scale distribution.
Firmware C rethinks the SFP+ port entirely. In most router configurations, SFP+ is a WAN port — you plug fibre in from outside and internet comes in. In Firmware C, SFP+ becomes a LAN trunk — a 10 Gigabit link that carries your internal network out to distribution switches, access points, and other equipment throughout a building.
The WAN uplink in this topology is cellular only. Internet comes in over 5G. The SFP+ carries that internet — and your entire local network — over fibre to wherever you need it. A large office, a warehouse, a hotel floor, a building with multiple rooms that need wired and wireless connectivity all served from one central router.
C1 — single modem. One 5G SIM feeding the entire building via SFP+ LAN trunk. Built and verified — this is in the hands of customers now.
C2 (Supreme) — dual modem. Two SIMs providing the WAN uplink, both distributed to the building over the same SFP+ LAN trunk. More bandwidth, more resilience. Coming with dual-modem hardware.
Multiple routers. Multiple SIMs. One bonded connection.
Firmware D is the top of the range — and a genuine step change in what a cellular router system can do. Multiple Rocket Routers connect to each other over encrypted WireGuard tunnels and pool every SIM card's bandwidth into a single bonded connection. Add a router, add a SIM, bandwidth scales. Lose a connection, traffic redistributes automatically. No manual intervention. No downtime.
This is what enterprise networking vendors charge thousands of pounds per month to deliver on managed contracts. Firmware D delivers the same capability on hardware you own outright, running software you can inspect and verify, with no ongoing licence fee.
Read the full Firmware D breakdown — including how bandwidth bonding works, what commercial equivalents cost, and who this is realistically for — in our dedicated post: Rocket Mesh — Multiple Routers, Multiple SIMs, One Bonded Connection →
Quick comparison — which firmware do you need?
| Your situation | Firmware |
|---|---|
| No fibre. Just want reliable internet from a SIM card. | A — Rocket Plus |
| Have fibre but need it to fail over to cellular automatically. | B — Rocket Pro |
| Need to distribute 5G internet throughout a building over fibre cabling. | C — Rocket Plus Enterprise |
| Need maximum bandwidth from multiple SIMs across multiple routers, with full redundancy. | D — Rocket Mesh |
| Not sure. | Get in touch — we will tell you honestly. |
On pricing — and why Firmware D costs more
Firmware A, B, and C ship with the routers they are designed for at no additional charge. The firmware is part of the product. You buy a Rocket Plus or Rocket Pro, it arrives configured correctly, it works.
Firmware D is different. A Rocket Mesh deployment involves multiple routers, multiple SIM cards, and a level of design and setup work that a single-router install does not. We are honest about this: the hardware cost scales with the number of routers, and for larger deployments we charge for the time to design, configure, and deploy correctly.
What you are paying for with Firmware D is not the software — that is open source and always will be. You are paying for the expertise to deploy it properly, the hardware configured and tested before it leaves us, and support if something goes wrong. For a venue or building site where internet downtime costs money, that is worth every penny.
To put it in context: A Peplink MAX BR1 Pro 5G — a commercial cellular router with similar capability to a single Rocket Plus — costs over £1,200 and requires a cloud licence to access most of its features. A managed multi-WAN enterprise solution from Cradlepoint runs to £2,000–£5,000 per month. Rocket Mesh delivers comparable capability at a fraction of that, with no monthly licence and no vendor lock-in.
Our source code — open, readable, and yours to learn from
Every line of firmware we write is built on OpenWrt, which is licensed under the GNU General Public Licence version 2 (GPL v2). This is a copyleft licence — it means that if we distribute firmware in binary form, we must also make the source code available. We think this is right, not just legally required.
Our custom configuration scripts — the ones that handle modem detection, failover setup, port configuration, LED behaviour, and all the rest — are published openly. You can read them. You can learn from them. You can modify them for your own use on your own hardware.
One rule we ask everyone to respect
We build this firmware to connect people — to give them fast, reliable, private internet access. We are proud of what it does and how it does it.
We ask — clearly and directly — that nobody uses our firmware, our tools, or our technology to harm people or harm computers. Not to attack networks. Not to compromise devices. Not to intercept communications maliciously. Not to facilitate anything that causes harm to a human being.
We cannot enforce this in code. No software can. But we can say it plainly, mean it genuinely, and let it stand as a statement of what this work is for. The overwhelming majority of people who use open-source networking tools are curious, skilled, and honest. This message is for the rare exception — and it is a simple one: this is not what we built it for, and we want no part of it.
Clear and simple: Rocket Routers firmware is licensed for lawful use only. Using it to attack, compromise, intercept, or harm any computer system or person is a violation of the terms under which it is offered — and in most jurisdictions, a criminal offence. If you find a security vulnerability in our firmware, please contact us responsibly so we can fix it. We will acknowledge your contribution.
Questions?
If you are not sure which firmware is right for your situation, or you want to talk through a specific deployment — get in touch. We will give you a straight answer, not a sales pitch. If our products are not the right fit for what you need, we will tell you that too.