wifi ac is a newer faster protocol. If I remember right it boasts lower latency and higher bandwidth than N. However having said that the GN2 will work with an AC router, (I bought one) - it will just operate with the N protocol and speed. Here's a snippet from cnet (link below)
Link to CNET article
"802.11ac supplements 802.11n
Netgear's first 802.11ac router, the WiFi 6300, is set to be available for purchase this month.
Netgear's first 802.11ac router, the WiFi 6300, is set to be available for purchase this month.
(Credit: Dong Ngo/CNET)
802.11ac (aka 5G Wi-Fi) is the next step after 802.11n (aka N or Wireless-N, which is currently is the most popular Wi-Fi standard). It's backward-compatible with N, meaning that a 5G Wi-Fi router will support N clients and 5G Wi-Fi clients will also be able to connect to an N router. Wireless-N, in turn, is backward compatible with the rest of the wireless standards, including 802.11g, 802.11b, and 802.11a. ..... Similar to Wireless-N, 802.11ac, for now, comes in three tiers, based on the number of streams. The more streams, the more bandwidth a device can handle. For example, Wireless-N has caps of 150Mbps with single-stream, 300Mbps with dual-stream, and 450Mbps with three-stream. 5G Wi-Fi connections are set to be about three times faster, starting with 450Mbps in single-stream, 900Mbps (dual-stream) and 1.3Gbps (three-stream). So technically, 5G Wi-Fi is the first wireless standard that breaks the gigabit barrier"