I’ll assume that you are not using WDM.
Many documents explains the way to set dhcp 161 and 162 options in the same way.
I recommend you to use an alternate FTP Server like Filezilla, because it displays a very usefull activity log window, to debug ftp/wyse download problems.
The main problem with ftp configuration on the wyses are the directory structure, that varies on different models.
So, stop IIS FTP SERVER, install FileZilla, create an anonymous user with a blank pass, assign it a directory (read only) then create your wlx.ini file to test, then you can check on the main window if your wyse terminal is connecting to the ftp server and what files and on what folders are trying to download the file.