I swapped out hybrid disc on my N1638 (the small one) with a full SATA Samsung EVO 850 SSD. In itself this worked fine, but I found the Intel 7265D wireless started to get very upset: timeouts, error messages and firmware restarts, etc. all consistent with 'platform noise' -- i.e. strong electromagnetic interference of some variety.
With the old drive put back in, everything is fine again.
So my best guess at the moment is that it is the SSD causing this (and there are reports of similar things on other machines out there), and there's a design limitation here -- possibly due to the wifi card being right next to the drive or an antenna near the touchpad. Either that or the SSD is faulty in some bizarre way.
Has anyone else popped an EVO 850 into an N1638, had this problem, and found a solution?
Update: Definitely think this is emissions from the EVO. I put it on a USB bridge and left it on the N1638 touch pad. Lo and behold, the same disruption. Then I put my phone on it running WiFi Analyser. When I switch the SSD on all the weaker APs in the nearby houses drop off the chart -- very telling! I'll have to try one of my other EVOs to see if this one's faulty.