Apologies for the delay in response, had a busy week and never got around to checking these forums this week.
The checkbox I left checked is "Allow the computer to turn off this device to save power" in the Power Management tab of the device properties in the device manager. The one that has corrected the issue with sleep for most people when leaving it checked.
The official 17.1.0 drivers from here (not the ones including PROSet, just driver only):
https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=24220
Unfortunately, at this time I do not have my device with me or I would tell you the additional version numbers, I'll remember to take a look at it next time I'm near it and let you know. However, I believe the version is 17.1.0.19
I can tell you for sure that at home my device is always on 5GHz at 500-650Mbps, I dont even have my 2.4GHz network configured on it. At work it is connected on the 2.4GHz band.
As for total use on my network at home, the vast majority of devices are on the 2.4GHz band. I believe this one and one other share my 5GHz band.
What I believe to be the reason it has remained stable is the lack of the PROSet software and letting Windows manage the wireless settings.