Strange Connectivity Issue

I have Lightburn on two Windows 10 computers, one a desktop hooked to wired ethernet and the other a laptop over WiFi. The Ruida 6445G controller is wired ethernet with a statically assigned IP of The two Windows machines are DHCP in the range of .2 to .199 (network of

The desktop computer has no problems connecting from Lightburn to the Ruida, the laptop however will not connect. The laptop IS able to PING and receive a response with 0 loss, so there is connectivity. Have done all the basic stuff like restart everything physically, release/renew DHCP leases, etc… But nothing has helped. Lightburn provides no good information or error back, just stays “Disconnected”. Portqry reports LISTENING or FILTERED, WireShark shows sending the UDP packets to the Ruida.

Long story short, something on my networking is blocking/filtering the UDP packets, has anyone ever encountered this?

Do you know you can ‘right click’ on the ‘devices’ button to attempt a re connect?

Is the laser on a wireless bridge or just on the network directly?


Yes, I have clicked, reselected and clicked OK on Devices a gajillion times at this point. And no, as stated, the Ruida is direct connect wired ethernet. There is a switch between it and both computers, but otherwise all the same network with VLANs or anything like that.

Yes, that should work. Since one works and the other does not, it has to be in the ‘does not’ part.

Sorry I’m not sure where to point you except you windows machine… I pretty much live on Linux.

Maybe one of the guys that works with Windows will give us a hint.


Issue resolved! Though not sure on what did it as I re-did a bunch of things at the same time, not very scientific but my annoyance factor was high!

So it’s back to configuration…?

So glad you’re back up.


What would you like LightBurn to say Donald?

… since it’s clearly NOT a LightBurn issue … it may be helpful for other users to have a bit more information as to what you have done to resolve this.

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Normally software that has a failure with throw some sort of error, whether that is to a log, or to a dialog box, etc…, some form of positive feedback to the user that an error occurred. The only thing that happens is a brief flash of the “Disconnected” and “Device not Found” text when it is refreshed. Additionally, it should also have an easily discoverable method of re-trying after a failure, as it is you either get lucky or read in the forum that opening the Devices dialog, selecting the device and hitting OK attempts a reconnect.

And this is the failure, LB is not able to connect to board via serial/com, i think there is no more infos that LB can give. LB can’t know if divers are installed or not so… the only info that can give is “Disconnected” or “Device not found”.

No, I’m talking about ethernet/udp, not serial. And they could/can determine if 1) the destination IP exists, 2) if it’s reachable by ping/icmp, 3) determine if the port is open. The issue I had was one of the UDP packets being filtered btw the host and the controller, which the software wouldn’t be able to determine. Ultimately, between resetting the Windows Firewall on the host to default and uninstalling/re-installing Ligthburn is most likely what resolved the filtered/lost UDP packets.

As a side note, Ruida choosing to use connectionless UDP multicast rather than a TCP based connection can cause issues if you have more than one laser and/or more than one Lightburn workstation. Anyone knowing the IP address of the Ruida controller can send any command at any time regardless of what the controller is doing. So if someone accidently selects the wrong device from the menu and then issues a stop command, a currently running job started by someone else will be terminated. Just something to keep in mind.

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I am having the same issues. I wonder what you did…

I believe it was resetting the firewall and then un-installing / re-installing LB.

Does this mean that two instantiations of lighburn on two different machines can successfully connect and talk to the same Ruida and there’s no way to tell?

I know it won’t work properly, but that’s not the question…