How does the "LAN only" mode works?

Hi,
Due to an error linked to the “Bambu cloud”, I decided to put my printer in “LAN only” mode. Moreover, I blocked all outgoing (to the internet) access of the printer.
But I discovered a fact that led me to try to understand better this “LAN only” mode: I’m still able to use Bambu Studio to send printing to the H2D from my computer. I checked two times, and the printer is in “LAN Only”, developer mode.
It means that my computer probably plays the role of a gateway between Bambu and the H2D. Which is logical, since the printer has always been inaccessible directly from the internet due to the NAT the router implements.
I can investigate further (by analyzing the traffic between my computer, the printer, and the internet), but does someone know how this “LAN mode” works really?

Regards

LAN only mode does not use bambu cloud at all, everything is simply connecting directly from your PC to your printer through your router. You will miss dedicated cloud only features like the use of bambu handy and the ability to skip parts and may be (except if it has been improved) access to timelapses and model history from bambu studio. I’m not sure if the model picture is still displayed on your screen as this was apparently coming from the cloud but it may have also been improved. The only internet connection which remains may be the time server request which is still sent and received through port 123 of your router.

If you fully disconnect your internet access and only use the wifi, it should work as well.

Hi,
thanks.
Actually, even in “LAN only” mode, the printer tries to reach local hosts by sending packets to 255.255.255.255 according to wireshark dumps.
“…NOTIFY * HTTP/1.1
Host: 239.255.255.250:1990
Server: UPnP/1.0
Location: XXX.XXX.XXX.XXX
NT: urn:bambulab-com:device:3dprinter:1
NTS: ssdp:alive
USN: 0948BB540201174
Cache-Control: max-age=1800
DevModel.bambu.com: O1D
DevName.bambu.com: BAMBU
DevConnect.bambu.com: lan
DevBind.bambu.com: free
Devseclink.bambu.com: secure
DevInf.bambu.com: wlan0
DevVersion.bambu.com: XXXXXXXXXXXXX
DevCap.bambu.com: 1”
Regards

How to enable LAN Mode on Bambu Lab printers | Bambu Lab Wiki

1 Like

That’s normal that’s the device discovery through internal gateway, Printer and router need to establish connection and that’s done through port 1990

I am using a wired-only router and connection to our X1-E printers. Based on our company’s firewall/security setup, we have to work entirely offline, so are trying to successfully configure LAN Only mode.

What we have set up is:

  • Both computer and printers share the same network.
  • Bambu Studio has been added to the list of applications that can pass through the Firewall.
  • On the computers, we have the network set up as private
  • The printers have an IP address automatically assigned, and we can successfully ping them via the command prompt.
  • In Bambu studio I am able to add the printers to the list of available devices using the Access Code and SN of each printer

However, when I try to select the printer from the list of available devices, I receive a “connection failed” error. Do you know of any resources that might help me troubleshoot this? It seems so close to working…

If it helps, this is also how my wifi is configured in Win11:

  • Connect automatically when in range: ON
  • Private network: ON Public: OFF
  • Random Hardware Addresses: OFF
  • Metered Connection: OFF
  • IP Assignment: Automatic
  • DNS Servers Assignment: Automatic

This works on my P1S, my H2D is connected to the cloud so cannot test it but there’s no reason it wouldn’t work the same.

1 Like

As of the latest version of Bambu Labs for MacOS 2.1.1.52 and whatever is the latest firmware for my P1S, LAN only mode does not work at all without an internet connection.

I had an internet outage for a few hours today and could not print anything AT ALL. Mind you, nothing was wrong with my local LAN. Bambu Studio had full connectivity to the printer. I could see the camera, query current state, ping the printer from my desktop, etc. But when sending a job(tried 30-40 times) Bambu studio would either crash right at the end of the Gcode download or throw a non-describe error message.

In short LAN only mode absolutely does not work without an internet connection on MacOS. This is horrible. I specifically researched this before buying and would not have bought it if it did not falsely claim to work without internet.

Did you try ferrying the gcode over by usb?
Probably a good option for others who may face your situation (internet outage).

Make sure helio is disabled. If was working pre 2.2.0 then I suspect some network dependency accidentally pulled in. If so, submit a ticket.

Edit: ah nvm, I see the 2.1.1.x

I admit I did not try this. I assumed it would work as a fallback and just kept trying to troubleshoot it not working over the network.

I did not realize there was already a newer version. 2.1.1 was the newest when I first downloaded Bambu Studio just over a week ago.

I’ll try 2.2.0.

If all else fails, you can always send the gcode to the as card, and then print from the sd card. Though, I completely agree that you shouldn’t have to do that. LAN Only literally means “Local Area Network Only” and does not say “Local Area Network (as long as your network is connected to the internet) Only”.

1 Like

Idealy cloud mode should fall back to LAN mode automatically in case of no internet. It looks like it doesn’t though.

While you could switch manually to LAN only, a USB stick is probably the easiest for a temporary internet loss.

LAN only mode (thank you for that BL, please never remove it!) does what it says and sticks to working solely local. I never used anything else.