Short version

In LAN-only mode, OrcaSlicer keeps dropping your Bambu Lab printer back to "unbound" and asking for the 8-digit access code again every time you close Orca, your PC sleeps, or the printer briefly goes offline. The cause is a field-name mismatch: Orca saves the code under user_access_code, but the Bambu network plugin reads it from access_code. The fix takes two minutes: with OrcaSlicer closed, open OrcaSlicer.conf and rename user_access_code to access_code.

Why OrcaSlicer forgets the code

This only happens in LAN-only mode, where Orca needs the printer's local 8-digit access code to bind directly. In cloud mode the authentication runs through your Bambu account, so there is no local code to lose and the symptom never appears.

It behaves like a regression: it was widely reported starting with OrcaSlicer 2.1.1, and the person who filed the bug noted the same printer kept working fine in Bambu Studio on the same machine at the time. Any disconnect is enough to trigger it: close Orca, let the PC sleep, or take the printer offline, and the printer falls back into the "unknown printers" list and demands the code again.

The root cause is a field mismatch that is really on the Bambu network plugin side (the same failure shows up in Bambu Studio, not just Orca): Orca persists the code under the key user_access_code, while the Bambu plugin looks for access_code. On the next launch the plugin finds nothing, so the printer is treated as unbound.

The fix: rename one field in OrcaSlicer.conf

Close OrcaSlicer completely first. Orca rewrites this config file when it exits, so any edit you make while it is running gets overwritten. Fully quit the app before editing, then reopen it afterwards.

In OrcaSlicer, add and bind each Bambu printer the normal way first (enter the 8-digit code from the printer display) so the entries already exist.
Quit OrcaSlicer completely.
Open OrcaSlicer.conf in a plain-text editor (Notepad++, VS Code, TextEdit in plain-text mode):
Windows%APPDATA%\OrcaSlicer\OrcaSlicer.conf (paste %APPDATA%\OrcaSlicer into Explorer or the Run dialog)

macOS~/Library/Application Support/OrcaSlicer/OrcaSlicer.conf

Linuxusually ~/.config/OrcaSlicer/OrcaSlicer.conf (Flatpak installs differ). Confirm the path on your own system rather than assuming.
Find the user_access_code section and rename the key to access_code. Save and close.
Reopen OrcaSlicer. The printer should now stay bound between sessions.

For reference, the block sits at the top level of the file and pairs each printer's serial number with its code:

{
  "access_code": {
    "00M09A1234567890": "48273916"
  },
  "app": {
    ...
  }
}

The key is your printer's serial number (on the printer under the Device menu); the value is the 8-digit LAN access code (Settings › LAN-only mode on the printer display). The serial above is only there to show the shape: copy your real serial straight from the printer menu, since the exact length and characters vary by model and batch. Multiple printers get one line each inside the access_code object.

If your printer is on a different subnet or VLAN

A separate problem with the same symptom: if the printer and the PC running Orca are on different subnets or VLANs (for example an isolated IoT network), Orca's automatic discovery never finds the printer, so it cannot bind in the first place, access code or not.

The community workaround is a small Python script, orca-find-bambu.py by patrikalienus (a public GitHub gist). It sends a crafted SSDP discovery reply to port 2021 on your PC and announces the printer to the slicer by hand, so it becomes visible across the subnet boundary. It is Python 3 with standard library only, so there is nothing to install.

Download the script and set the variables at the top: PRINTER_IP, TARGET_IP (the PC running Orca), PRINTER_USN (serial number), PRINTER_DEV_MODEL (model code: the gist example C11 is a P1P, other models use different codes, so check yours) and PRINTER_DEV_NAME.
Start OrcaSlicer first, then run python orca-find-bambu.py.
The printer appears in Orca and can be bound with the access code as above.

The announcement is temporary: rerun the script after an Orca restart, or run it as a scheduled task if you want a permanent setup.

Caveats and what this does not fix

Not the same as "won't connect at all." This article is about Orca forgetting the code. If Orca will not connect or keeps dropping the connection entirely, that is usually a different cause: a router restart, an FTP upload error (-4020), the newer firmware authorization system, or a Home Assistant integration holding the single local connection. Those need different fixes.

Not guaranteed permanent. Even with the correct key, the code can be lost again if the PC sleeps or the printer goes offline while Orca is running. This fix stabilizes the normal case; it is not a cure-all.
Newer OrcaSlicer versions may not need it. The underlying bug (issue #6169) was merged and closed as completed in February 2025, so on current builds the symptom may not occur at all. Keep this config trick as a fallback if it returns.
Firmware authorization control. On Bambu's newer authorization-control firmware (P-series from 01.08.02.00, A-series from 01.05.00.00), third-party software may first need Developer or LAN mode enabled on the printer, or Bambu Connect, before it can connect at all. Make sure Orca is allowed to connect on your firmware, then apply this fix.
Home Assistant conflict. If you run the ha-bambulab integration at the same time, it can hold the printer's single local connection and block Orca. Separate issue, but often seen together.

The bottom line

A two-minute config edit fixes the most annoying part of running OrcaSlicer with a Bambu printer in LAN-only mode. If your version already keeps the code, you do not need it. If it starts forgetting again, renaming that one field is the first thing to try.

More troubleshooting Bambu firmware guide Bambu software & ecosystem

Sources: GitHub SoftFever/OrcaSlicer issue #6169 ("Orcaslicer forgets access code for X1C in LAN mode constantly") for the cause, the config-file fix (the user_access_code to access_code rename), the macOS/Windows paths, and the version/firmware context; the patrikalienus GitHub gist (orca-find-bambu.py) for the cross-subnet SSDP script; Bambu Lab's firmware blog and 3D Printing Industry for the authorization-control context. The Linux config path and the exact serial-number format vary by system and model and should be verified on your own machine (marked as such above rather than stated as fact).

OrcaSlicer Keeps Forgetting Your Bambu Access Code (LAN Mode): The Fix