nano disconnecting

I have a bunch of nano clones(12 of them) hooked up to a windows 10 pro pc via a powered usb hub.. I have multiple sets of these running(about 10 windows 10 pc's)..

The nano's are used for powering led's and reading button presses via I2C.. I am using standard firmata..

and have been using this setup for months and months without any problems what so ever, when starting 2 days ago, the nano's would randomly drop out and the only way to correct the problem was to unplug and replug them back in.. Its only happening on 2 of the 10+ pc's.. I have replaced the pc, usb hub, cable, etc..

Any ideas what could be causing this or if there was a windows 10 update that would have affected this?