I had two laptops, personal and work, both with the Intel ac7260 card in them, both extremely problematic especially with linux. Subsequent Windows drivers made them about bearable but Linux never worked.
In my personal (Dell) I swapped the card for the older 6235 card and everything was perfect.
In my work (Lenovo) laptop I had to invoke customer support as a faulty card, they replaced it, it was much better in Windows but still bad in Linux.
There was a massive discussion on the Intel support forums about the card, so I think the first version/early product runs were faulty, Intel never admitted to it.