ScanApp Lei v1.5 disconnecting after every scan

[Max_]

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. 

[DerrickL]

Outdated firmware may cause the scanner to loose network connection. There is a firmware update  dated 1/22/26 on Canon's support site here:

https://www.usa.canon.com/support/p/imageprograf-tm-240-mfp-lm24-1

[Max_]

That firmware is for the TM-240, not the Lm24 scanner that is attached, which is what I'm having issues with. They run on separate firmware and software. Under Scanner Info its listed as Fw: 5.06.04 (106563)

[Dastan]

I have the same problem

[DerrickL]

I researched this is issue a bit more and wonder if this is relevant to it:

ScanApp Lei Error Messages Message Please Connect to a Supported Printer. No Scanners Found Error. User Action The ScanApp Lei will needs at least one of the supported printers to be present on the network and checks periodically for the printer. This will not normally affect use of the system, but on occasion you may see this message. To eliminate this message, power on the printer, then press the Refresh button in the ScanApp Lei. The ScanApp Lei is unable to connect to the scanner. See Operational errors. No Printers Found Error. The ScanApp Lei is unable to connect to the scanner. See Operational errors. Internet Connection Error. Power cycle scanner and restart ScanApp Lei. If problem persists, call service. Invalid File Error. Power cycle scanner and restart ScanApp Lei. If problem persists, call service. PDF File Error. Power cycle scanner and restart ScanApp Lei. If problem persists, call service. File Resend Error. Power cycle scanner and restart ScanApp Lei. If problem persists, call service. Version 1.00 31 Global Scanning UK Ltd © 2018

[shadowsports]

Greetings,

For support of these items, I would contact Canon large format printer support for support or direction.

1-800-423-2366

It's possible these products are supported by Canon's Dealer Network, but you'll have to ask.

The community is geared towards Canon standard consumer products. I think you'll get quicker resolution using the contact information I provided above.  If they can't help you, they will guide you to the party who can.