Using 'cat' is not a good way to ever use a serial port. Please use a tool that can properly detect and use the serial port flow control settings, which should prevent the issues you are seeing here. Is socat using flow control? If so, which settings, hardware or software flow control? Also please note that the usb-serial devices you are using here are _very_ cheap and not good for huge amounts of data like you seem to want to use here. I would recommend a much more robust usb-serial device if you need high data rates and good hardware flow control handling. Most of the time, the devices you have here do not even have any hardware flow control support as the manufacturers do not hook up those lines. So be careful. thanks, greg k-h
Yes, you are right! Such gadget hardware is without hw flow control. I am using serial line only to capture console logs. I've tested both commands also with sw flow control ixon, ixoff with similar results. Hopefully somebody sitting on scarce big iron with both usb port and serial port with proper hw flow control from this list gets attracted to kindly re-test. Interesting part for me is that only serial to usb direction is failing.. Thanks, Filip Zaludek