@Vinny Thank you. Disabling AES-128 Encryption gave me more speed, up to 6Mbit/s

@Chad-Sweet Thank you

Please confirm if my understanding is correct.

1. Once we have connected Microhard USB dongle to PC we have virtual COM port. (Ground module)
2. On the other side of VOXL Microhard modem we have serial I/O and we can connect it to Pixhawk telemetry port and use Mission Planner (Air Module)

@tom Yes, that is exactly what I've tried to do.

Here are the settings which are the most stable for me.
The most important TX Rate for me, because it affects connection quality.

The fist three "64-QAM 5/6 FEC", "64-QAM 3/4 FEC", "64-QAM 2/3 FEC" are not working for me, no connect at all. With the rest of options I can get 1-3Mbit/s speed but not more.
All other settings have default values.

So I'm just curious, if it is really possible to get 25Mbit/s or not?
Has anyone achieved 25Mbit/s?

What is the maximum communication speed for pDDL1800?
I have got stable connect with only with 3Mbit/s, but it is declared as up to 25Mbit/s

What are the conditions for 25Mbit/s connection? Some specific settings or anything else?