Hi everyone,
I’m hoping someone can help me resolve a persistent connection issue between my xTool F1 and LightBurn Core 2.0.05. I have done extensive diagnostic work and have detailed findings to share which I hope will help identify the exact cause.
My setup:
- xTool F1 (firmware 40.51.020.2020.01.ht4)
- LightBurn Core 2.0.05 (licence purchased directly from LightBurn, recently renewed)
- xTool-F1-V2.2.lbdev configuration file imported
- Tested on two computers: Dell laptop (Windows 11) and Microsoft Surface Laptop 3 (Windows 11)
- Connection method: USB cable
- xTool Studio v1.6.8 also installed (connects to F1 successfully)
- I previously connected successfully to the F1 using LightBurn on the Surface Laptop 3
What I have confirmed is working:
- The USB cable and connection are good — xTool Studio connects to the F1 without any issues on both laptops
- RNDIS driver is correctly installed on both laptops — the F1 appears in Device Manager as “Remote NDIS based Internet Sharing Device” under Network Adapters
- The F1 has a confirmed IP address of 172.25.3.1 over the RNDIS USB connection
- Ping to 172.25.3.1 succeeds with 4/4 replies, 0% packet loss, under 1ms response time
- On the Surface Laptop 3, a static IP of 172.25.3.200 has been set on the RNDIS adapter to ensure correct subnet assignment
Detailed diagnostic findings:
Using netstat -an | findstr 172.25.3 while LightBurn is attempting to connect:
- Port 8780 (the port in the original xTool-F1-V2.2.lbdev file): consistently returns SYN_SENT on both laptops — the F1 is actively refusing this connection
- Port 28900 (the port xTool Studio uses — confirmed by running netstat while xTool Studio was connected): returns ESTABLISHED — LightBurn can connect at network level but the F1 does not respond to any GRBL commands (tried
$and$Iin the Console — no response) - Port 80: open, returns “Access Forbidden” HTML response
- Ports 23, 8080, 8765, 8888, 8000: all closed/refused
- Port scan 8700-8800: no open ports found in this range other than 8780 being refused
The xTool-F1-V2.2.lbdev file has been edited to set the IP to 172.25.3.1. Tested with both port 8780 and port 28900.
What I have tried:
- Installing RNDIS driver via xTool support page driver package
- Manually setting static IP on RNDIS adapter
- Editing the .lbdev file to correct IP address (172.25.3.1)
- Editing the .lbdev file to change port from 8780 to 28900
- Creating device manually in LightBurn as GRBL/Ethernet TCP
- Closing xTool Studio completely before opening LightBurn
- Testing on two completely different laptops
- Power cycling the F1
- Renewing LightBurn licence
- Updating LightBurn to 2.0.05
Key observations:
- Port 8780 is refused on both laptops — this appears to be a firmware issue as the F1 previously worked with LightBurn on the Surface Laptop 3
- Port 28900 establishes a TCP connection but the F1 does not speak GRBL on this port — it appears to be xTool’s proprietary protocol used by xTool Studio
- The F1’s current firmware is 40.51.020.2020.01.ht4 — I suspect a firmware update may have changed or closed the GRBL port
What I need help with:
- Is port 8780 the correct GRBL port for the F1, and if so why would it be refused?
- Has anyone seen this issue with firmware version 40.51.020.2020.01.ht4 specifically?
- Is there a known firmware version that works reliably with LightBurn, and is downgrading possible?
- Is there any other port or connection method that should be used for LightBurn with the F1 over USB/RNDIS?
Any help would be greatly appreciated. I have put a huge amount of time into diagnosing this and am confident the information above covers everything needed to identify the root cause.
Thanks in advance.