Wifi is pretty unreliable as it is right now. Wi-fi vastly undercuts your internet speed. Most ISP's provide a certain speed, but the speed is only guaranteed when wired directly into the router.
ISPs don't have control of the speeds between two devices on the same network; only speeds between two networks connected via the internet. A phone and computer on the network can transfer data as fast as the slowest network adapter or router, permitting that nothing else is using the connection. My router can push ~356 Mbps to a device via WiFi, if the device supports it, and I think 1 Gbps through a wired connection, if the device supports it. However, I wonder how much information the HoloLense is processing every second. It shouldn't be an extreme amount, looking at the size of the device.