With a Lenovo t440 2 month old I am having the same problem. I did try all the options changed. The driver is up to date 17.1xx form the installer on the Intel WEB site. So even with the latest driver it is still responding to ping unconfidently. When the cart go on I have 8 ping less the 2 ms and then it start to change from 2 MS up to 1440ms and event some time no reply.
This problem does exist for a long period of time. How come Intel is not able to fix it?