BambuLab A1 printer - LAN Mode - Firewall rules

By default, BambuLab 3d printers are connected via the Cloud - you upload your print files that way and you also can monitor your printer from anywhere in the world in that way.

However, there is also a LAN mode where data flows between your computer running BambuStudio and the printer via your in-home network.

I decided to create a separate VLAN for my 3D printer where it would be isolated from all my other machines. Unfortunately this created a problem in that my MacBook running BambuStudio would not detect the printer.

Here is how I solved it:

• On this link, BL publishes this information that tells us how the printer announces itself on a network.

    

• So the task at hand is to make sure that broadcast/multicast packets that the printer spits out make it to the VLAN that your computer is on. Let's assume that my computer is on VLAN A and my BL printer is on VLAN B. In my case I am running an OpnSense firewall and so there are 2 initial rules that come into play:
• Rule 1:  VLAN A has full access to VLAN B
• Rule 2:  VLAN B is blocked from accessing VLAN A - this is the intentional isolation of the BL printer from my network.
• Next, I installed the UDP Broadcast Relay plugin and configured two rules under that;
• Rule 1: Propagate broadcast traffic to the multicast address of 239.255.255.250 / port 1990 between VLAN A and VLAN B
• Rule 2: Propagate broadcast traffic on port 2021 between VLAN A and VLAN B

Voila - the printer now showed up on my computer with BL Studio in LAN mode and I have been happily printing and monitoring ever since.