Hi, i have a problem with my moonlander 2.

I have a Raspberry Pi3 and 2 Moonlander2 on a 20W powered hub.
After a bit of work, one of the two moonlander go to 0 Mhz. Sometimes after 10minutes, sometimes after 48 hours of good work.

I try to reset raspberry and change the hub with another one but the problem persists.
I try to change the frequencies from 600 to 796 but the problem persists, i don't change any voltage.

Do you have any advice?
Thank you.

https://preview.ibb.co/iGTQrL/raspimining-LI.jpg