I have always had intermittent USB hang up with the W8681 with the Meteobridge (also with a laptop running Cumulus).
The station could run for 1 or 2 days or more without a problem, sometimes only a few hours, there was no pattern.
My solution was to fit two clip-on ferrite rings (just a loop through the ring), one on the power (USB) cable and one on the USB cable between the Meteobridge and the W8681.
Since fitting them I've had no problems.
It seems that the W6861 USB is susceptible radio frequency interference the WIFI.
John in UK.