Hi !
I had the same issue :
Plot twist, it was file related. Everything is fine with another file…
For the file that was bugging me, I created a new project, and imported as geometrie only from the first one. Problem solved.
!!EVERY DAY I GET THIS ISSUE!!
I run 6 printers are every single day at least one of them does this. Sends the file perfectly fine to the rest. but its ALWAYS ONE that does it. Not the same one every time. But at least one a day does it
HAVE TO power cycle it at least 2 times to get it to work. And enter that redundant code to be able to connect each time.
If its on a closed lan server. WHY AM I PUTTING IN A SECURITY CODE?!
So annoying.
Why haven’t they fixed it yet?!
This was it for me today!
Switched to LAN only today and the first print attempt failed to “connect ftp” - did all the reboots and updates to no avail. Exported the object from the 3mf to STL, created a new project and imported the STL and it sent fine. It does seem something in the 3mf is expecting Cloud service.
This is exactly the issue that I’ve been having. I’ve tried everything that you did, including getting a new SD card. It’s exactly the same. It seems to be a roll of the dice each time. Has anyone submitted a ticket to Bambu?
Same FTP problem started here just last night on a P1S, did all the power cycling on networks, MAC and printer, plus tried many suggestions from here - BG,I’m printing my own large stl file (after splitting in two) in LAN mode, it has never given a problem since new/2023
Anyway I got it fixed, I put a used SD card in and formatted in the printer, sent the same file that failed 20 times, and this time it printed!
Hi all,
Happy New Year!
This is my first post here.
I’m really frustrated.
I can’t print directly from Bambu Studio, but I can send the file, go to the Printer tab → Memory, and start the print from there. Live View via LAN also works. Basically, everything works except direct printing.
I switched to LAN mode some time ago, and from the very beginning I’ve had this FTP sending error. I tried removing all Bambu Studio files, but nothing helps.
By the way, I forgot to mention that I have the H2D and Bambu Suite for laser work as well.
And finally, the icing on the cake: on my wife’s laptop everything works perfectly.
I have Windows 11 Pro, my wife has Windows 10 Pro, but I have no idea if that matters.
Do you have any suggestions?
Ok, I turned off and on again Windows defender firewall and now is working. We will see how long 
LAN only mode is mandatory for me.
In my case the issue with error code -4020 started, as I disconnected my Bambu software from the internet (I blocked internet access for Bambu Studio using the Windows firewall and blocked the MAC address from the printer using my router).
Now “send” works, but “Print plate” does not work any more. I can live with that, knowing that Bambu is not able to track my activities any more. This is definitively the first and last Bambu printer I purchased.
Sorry to hear about your issues. This has been an intermittent bug for a long time. I can however assure you can run a bambulab printer in lan only mode and NEVER have it connect to the internet. I have been doing so since I got my printer a few years ago. The newer slicer has gotten better with regards to local network connectivity however believe it or not I have found the Orca slicer is even better even though it uses the same network code base. Im currently using Orca slider 2.3.0 and have not had any issues what so ever. It just works.
Thanks for your advice.
I found another trick to overcome the issue: If I click the “print plate” button after slicing and switching back to “prepare”, it works perfectly. With this “workaround” I can live.
Still: This cloud addiction of Bambu-software and -devices is a no-go for me.