joe_intel,
Thanks for not really helping at all.
1) I do not consider the Windows network stack being partially broken to be 'cosmetic'.
2) I already stated that while I had this problem with the Lenovo provided drivers (which I do not believe are customized anyway), I ALSO had the problem using Intel provided drivers both 15.6.1 and 15.8, both on a domain-joined system and on a freshly formatted system.
And I am not even the first person to have had this problem, because the OP had the problem on a Dell Latitude notebook! You haven't helped him and you aren't helping me.
The way I see it, Intel has changed something significant with the driver packages 15.6+, and this is affecting some systems, even if it is only in rare cases. This should be investigated!