Hi Alezis,
because of my weekend family activities, I just got here.
Please, if the problem is still current, visit my web page where you will find an answer to the solution.
I have v3.0 hardware from NanoVNA (it may be a July 2019 production) that I have converted to be much more capable in its current state. You can read the description here:
I hope you can solve the problem after reading the above.
You can also install the latest firmware.
73, Gyula HA3HZ
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*** If you are not part of the solution, then you are the problem. ( ) ***
Gyula Molnar