For general Network issues found on Windows 10, we have written a few articles you can see under related posts section.
Update the adapter and restart Surface Pro 4. If the Sluggish WiFi Connections in Surface Pro 4 persists even after you change the value of the aforesaid registry key you need to go through the network adapter.
HKEY_LOCAL_MACHINE => SYSTEM => ControlSet001 => Services => mrvlpcie8897 If you cannot connect your computer to the network, troubleshoot this. How to Fix Sluggish WiFi Connections in Surface Pro 4 A future update will bring a fix for this but for the time being, this registry tweak will subside the issue. The problem is especially concerned with the MAC layer aggregation (A-MSDU over A-MPDU) and just affects a little subset of access points. 41 which results in transferring data at an outstanding slow rate with a particular access point generated when you access the network. The detailed cause has been pointed by a Microsoft engineer where he mentions that the problem is known with.
