I have recently upgraded my 5-year-old Vaio notebook to a Dell XPS 13 9350 netbook running Windows 10.
The reason for the upgrade was that my Vaio battery is dying (again) and because the Dell had wireless ac.
The Dell comes highly recommended, and is a fine little unit with one major weakness - its wireless performance - which is markedly inferior to the Vaio.
I have a good home office wifi setup with a strong signal:
HFC cable 100/10 Mbps > Cisco modem > Ubiquiti Edge router > Cisco switch > Ubiquiti UniFi WAP
The WAP is the latest second-generation UniFi AP-AC-LR with the latest firmware.
I have installed inSSIDer on the old Vaio and the new Dell - both show link scores of 100 on both the 2.4GHz and 5 GHz bands, with no overlapping channels. Signal strength is better than -50dBm.
The old Viao (wireless n) gives me 100% of line speed - 100/10Mbps.
The new Dell (wireless ac) gives me 50% of line speed or (much) less - as bad as 10 Mbps - used in the same location.
The Dell has a Broadcom network controller (Device PCI\VEN_14E4&DEV_43A3&SUBSYS_00211028&REV_08).
I am using the latest Dell Wireless 1820A 802.11ac driver (version: 1.555.0.0 - 26 Nov 2015)
Am I missing something obvious? - or do I just have to wait for a better driver?