I am myself working on an AP driver project. I noticed that when our AP send a fragment frame (I mean 802.11 fragmentation not IP fragmentation) in TKIP encryption, Intel 5300 just reply with two encrypted un-fragmented frames, and then the AP reports MIC error which put the station offline.
Literally, without any prior fragment setting for this station, the fragment setting of the AP should not effect the station fragmentation behavior.
The same problem doesn't appear on station using Atheros chips. The Atheros chip responses a single TKIP packet instead of two, and no MIC error happens.
The 5300 driver version is 18.104.22.168.
Is there anyone who knows anything about it? Much appreciated to know !
Have you try using are more recent drivers the 15.1?
Please let me research your inquiry and will get back to you as soon as I have more about this.