I too have repeated issues with Marvell AVASTAR WiFi Driver failing. Sounds dumb but easiest fix is to restart. I had Microsoft in San Diego mall fix it, but they reloaded the driver. I paid for Office Depot support in Vegas two separate times to uninstall and reinstall the driver, as I didn't have online access to get the driver. This happened about two months apart. It seemed like a good idea was to carry around a thumb drive with Marvell AVASTAR preloaded for emergencies. Then I went to Las Vegas mall Microsoft two months ago and she restarted it. No worries. It did it again tonight and I forgot about the quick fix while I was browsing the forum. Worked like a charm. I think many times I don't shut down or restart the Surface, I just close laptop. It may be related to this? Hope this helps.