That's what is causing your lag. That ping spikes would literally kick you out of the server. A consistent ping of 1 - 20 ms to the router is needed for lag free connection. It might be something to do with WiFi interference. Since you have a 5 GHz capability with your laptop, I highly recommend for you to use it instead of connecting to 2.4 GHz since there are a lot of noises that interferes with that frequency. If you live in USA, a cheap $ 25 Netgear Refurbished WNDR3400v1 router on Amazon is all you need (this is my secondary router/AP by the way and it's only broadcasting 5 GHz). You can set that refurb router as an AP so that you can still use your primary router. My primary router is Netgear WNR2000v2 since I have other devices that need the 2.4 GHz band. I stream media through WiFi a lot so I needed minimum RF noise which the 5 GHz band deliver.
BTW, if you're interested with the 16.8.0.6 drivers, you can download it from the Dell site here: Driver Details | Dell US