The DX11 dates back to the days when there were only 128 Presets. I think you still got the 32 User locations (typical for FM synths of the 1980s)

The MONTAGE by contrast has 2,707 Preset (many with multiple sound) and some 5,760 location for your programs between the User Bank and the 8 Library locations. The 128 sounds in a Bank became a standard throughout MIDI.

Today’s gear have tons of Banks of 128 Program using MSB/LSB messages to define the Bank selection, and then 128 Programs per Bank.

The DX11 was able to send Program Changes, but I’m afraid it pre-dates Bank Select by a few years. You will be able to Send only Program Change messages 001 through 128.

If in Single Mode, Hold Single and use the first ten buttons to send a three digit Program Change.
If in Performance Mode, Hold Performance and use the number button to send a three digit Program Change.

If you are sending MIDI from the DX11, set the MONTAGE to MIDI I/O Mode = Single or Hybrid so that you can play Multi Part Performances on a single channel. On the MONTAGE you will only be able to select the first 128 programs from the DX11. This will not be really viable as a selection device for MONTAGE.

You may want to look into other options to remotely select programs.

Thanks for your reply!!!!
Another question is, is it possible in the future to simplify this conversion through the operating system, especially with dx11, because in Serbia we still use dx11 for our folk music most of the time. The problem is that it cannot be fixed anymore is old but it suits us best for our music !!! THANK YOU ....