Bambu LAN-only and Developer Mode: what you lose
Updated 30 October 2026
To control a Bambu Lab printer from third-party software on current firmware, you need both LAN-only mode and Developer Mode. You lose Bambu Handy and cloud printing, firmware updates move to an SD card or a temporary return to the cloud, and Bambu does not support the mode.
We print motorcycle parts on three P1S and one X1C, and we wrote our own driver for them.
What each mode does
| Cloud (default) | LAN-only | LAN-only + Developer Mode | |
|---|---|---|---|
| Bambu Handy app | Yes | No | No |
| Remote start through Bambu's cloud | Yes | No | No |
| Third-party software can start prints without Bambu's authorisation | No | No | Yes |
| MQTT, live stream and FTP open without that check | No | No | Yes |
LAN-only mode takes the printer off Bambu's cloud. Bambu's wiki says Handy is not available in LAN mode.
Developer Mode turns off the authorisation check for local control. In Bambu's words, it leaves "the MQTT channel, live stream, and FTP open".
LAN-only alone is not enough. Software can connect, but the firmware rejects every command it sends. Our own setup notes record this, and it is the mistake we would check first. PrintStash reports the same: status can be read, but jobs cannot be started.
In cloud mode, SimplyPrint reports that Bambu's Authorization Control System blocks third-party software from starting prints, heating or moving axes.
How to enable both
These steps follow Bambu's wiki and SimplyPrint's guide (updated 25 May 2026). Menu names vary slightly by model.
- On the printer's screen, open Settings, then WLAN (or Network).
- Select LAN Only Mode and confirm.
- Power-cycle the printer. SimplyPrint says this is needed the first time.
- Scroll down in the same menu to Developer Mode, accept the risk notice and enable it.
- Note the IP address, serial number and access code.
SimplyPrint lists where the option first appears:
| Series | Developer Mode from firmware |
|---|---|
| X1 | 01.08.03.00 |
| P1 | 01.08.02.00 |
| A1 | 01.05.00.00 |
| H2D | 01.01.00.01 |
| P2 | From the start |
Recheck the access code whenever a printer stops connecting. SimplyPrint says it can change after a firmware change, and that toggling LAN-only did not change it in their testing. Our own setup notes say toggling refreshes it.
Exactly what you lose
Bambu Handy. The app stops working for that printer, because it requires cloud mode.
Cloud printing and remote access. XDA's write-up (March 2026) calls losing remote sends from Bambu's app a meaningful loss.
Cloud binding. PrintStash says a printer in Developer Mode can no longer be bound to Bambu Cloud while the mode is on.
The easy firmware route. Updates through Handy are gone, so someone has to make checking for firmware their job. SimplyPrint describes two routes:
| Route | Steps | After |
|---|---|---|
| Offline (their recommendation) | Download the firmware for your exact model from Bambu. Do not unzip or rename it. Copy it to the root of a microSD card (X1, P1, A1) or USB stick (H2D and newer). Choose the offline option under Settings → Firmware. Allow 10 to 20 minutes without power loss. | Both modes stay on |
| Temporary cloud | Disable LAN-only. Scan the QR code with Handy to bind the printer, because disabling alone is not enough. Install the update. | Re-enable both modes by hand |
What Bambu has said
20 January 2025. Bambu's blog post introduced Developer Mode as an option:
"This feature must be manually enabled on the printer, and users who select this option will assume full responsibility for securing their local network environment."
"Please note that Bambu Lab will not be able to provide customer support for this mode, as the communication protocols are not officially supported."
The same post says "This is NOT about limiting third-party software". It also says farm software vendors can work directly with Bambu "to implement proper authorization controls".
May 2026. During a dispute over a cloud-enabled OrcaSlicer fork, Bambu's forum announcement pointed users back to these modes:
"We would also like to remind our advanced users who want more control over their devices, that Bambu Connect, Lan Mode and Developer Mode are available, if the cloud connection is not your first choice."
Neither post promises how long Developer Mode will stay. On warranty, All3DP reported on 20 January 2025 that Bambu's head of PR confirmed Developer Mode will not affect it. We could only read that through search excerpts, so get it in writing if it matters to you.
Is it risky for a farm
In our opinion the risk is real but acceptable, if you plan for it.
- No vendor support. Bambu has told you in advance that it will not help with this mode.
- Network security is yours. The control channels are open on your network. Keep printers on a separate network segment. Our driver only needs MQTT on port 8883 and FTPS on port 990, plus the camera.
- An unofficial protocol. PrintStash notes it "has changed across firmware releases". Update one printer first and run a real job on it before you update the rest.
- A policy that has moved before. January 2025 showed that a firmware update can change what third-party tools may do.
One thing gets easier. Your printers no longer depend on Bambu's servers, because the connection stays on your own network.
What could change
As of 30 October 2026 we found no announcement removing or restricting Developer Mode. PrintStash, checked 18 August 2026, quotes Bambu's integration guide as saying the mode "does not require authorization verification" and that third-party software "will continue to work without any modifications". We could not open that guide directly.
Bambu could still restrict the mode in later firmware. The loudest current dispute is about something else. On 18 May 2026 the Software Freedom Conservancy alleged two AGPLv3 violations, about Bambu's networking library and the fork. Bambu later regretted that its wording "came across as a legal threat". SFC's post does not mention LAN or Developer Mode, and we found no final outcome.
Sensible hedges:
- Keep the offline firmware file for the version your fleet runs.
- Before buying more Bambu printers, check the current firmware notes for your model.
Three things we learned writing a driver
FAILED does not mean failed right now. The firmware keeps gcode_state at FAILED until the next print starts, even after the error is dismissed on the screen. Our first version read that as an error for good, so the queue waited for the printer while the printer waited for a job. Treat it as an error only while print_error is non-zero.
The first seconds after sending a job lie. A Bambu keeps reporting the previous print's FINISH or FAILED for a few seconds after a new job is sent. Ours marked jobs done in under a minute without printing. Only count a job finished after you have seen it printing.
The P1S camera fails silently on a bad handshake. On a real P1S, a wrong stream type in the port 6000 auth packet was accepted over TLS, and then nothing came back. With the right value (bytes 4 to 7 as the uint32 0x3000) we got about 15 KB of JPEG per second. The X1 series streams H.264 instead.
Our manual for connecting these printers to Rackrew is Bambu Lab setup.