RE: XPS 13 9350 - SSD on USB C 3.1 - very unstable/unusable
In device manager, double click on the wireless device and then go to Advanced tab. Scroll down in there, there should be a Transmit Power setting. For my Intel 8260, the settings are Highest - Medium High, etc. (I set it to Medium High). On my old 1820A card, I recall the settings being in percentages.