Hi, 

I want to run wan aggregation between my cable modem and my archer c5400x. I have a netgear cm 1200 cable modem that supports: LACP-IEEE 802.3ad and cannot get the 2 units to accept the aggregation.
 

I enable WAN aggregation on the router and reboot it. It shows it is enabled.

I enable Ethernet port aggregation on the cable modem (which clearly labels its aggregation format as IEEE 802.3ad LACP) and the cm says "Ethernet port aggregation status: inactive". 
 

my question is: what format / protocol is the archer c5400x's wan aggregation running?