SAP GUI 750: maximum work process hold time exceeded

Hi,

I have got an issue reported by two business users.

could you advice how to find out the cause for this error?

[Error message]
maximum work process hold time exceeded
This may be caused by network problem or slow front-end systems

Component: DPTM
Release 749
Version 10
Return Code -21
Counter 1

[Background]
The user see this error few times in a day.
The PC was connected to Wifi or LAN cable.
It happened during a registration, searching, printing and also when the user is doing nothing

[System specs]

OS: Windows10

Component: SAP Logon for Windows

Release: 750 Final Release

File Name: saplogon.exe

File Version :: 7500.2.9.1154

Build: 1904271

Patch Level : 9

Hotfix: 2

Thanks and Regards,