Setup:
- Canon imagePROGRAF TM-240 MFP Lm24 scanner
- ScanApp Lei v1.5 (build 97912)
- Windows 11, wired Ethernet
- PC: 192.168.0.85, Scanner (Lm24): 192.168.0.252 (static), Printer (TM-240): 192.168.0.251 (static)
- Single unmanaged switch, all devices on the same subnet
- Firewall disabled on private network, Lei running as Administrator
The Problem: ScanApp Lei shows "Please Connect to a Supported Printer" after 35 seconds of the application running or running in the background. The scanner displays "Waiting on PC." The only fix is to task-kill Lei and reopen it. This repeats every session.
Diagnostics performed:
Using Windows Resource Monitor, I confirmed that Lei establishes a single TCP connection to the scanner on port 710 when transmitting files during that 30 sec window. The scanner is fully reachable, pinging in CMD returns 0ms with zero packet loss. However, the TCP connection on port 710 drops after 35 seconds regardless of whether there is a current scan going through; it finishes the scan, then drops the connection, after which Lei cannot recover the connection without a full restart.
I've confirmed this is the scanner dropping the connection from its end, not the PC, as this is site-wide. The scanner appears to have an aggressive idle timeout (~35 seconds) despite its sleep set to 60 min, and is not responding to Windows TCP keepalive packets even when set as low as 10 seconds.
What I've ruled out:
- IP address issues — scanner is static, correct IP confirmed in Lei config
- Firewall — disabled on private network, Lei has inbound rules
- Network hardware — single unmanaged switch, direct Ethernet connections throughout
- Antivirus/file interception — scan files, write successfully
- Disk speed — local SSD, files land correctly
- NIC power management — disabled, set to maximum performance
- Windows TCP keepalives — tried 30-second and 10-second intervals, scanner ignores them
- VPN software — none installed
- Wrong IP in Lei config — verified correct
- Windows version compatibility — not using any Windows-specific scan protocols
Questions:
- Is there a Scanner Settings menu option to increase or disable the idle TCP timeout? (Cannot confirm as the settings PIN is unknown. The default 0000/1234/1111/9999 is not working)
- Is there a firmware update for the Lm24 scanner that addresses this, as I've only found 1.5 from https://scanner.support/mfpdownload/Lei/ as of 25/07/2022?
- Is there new software that I'm missing, as Lei has been depreciated?
Any help appreciated, even if it's just a workaround.
