My AC88U loses WAN connection at least once a day. It usually happens after I turn on a device that is LAN wired (not always right away). I'm running the latest ASUS firmware (3.0.0.4.380.3341). I created a ticket with ASUS and they told me to flash an older version of the firmware. I tried to do that unsuccessfully and haven't had a response from them since 7/8/16. My ISP is Mediacom and the DHCP lease time is 3 days. Everytime I lose WAN connection, the following 3 lines are in the system...
RT-AC88U loses WAN connection
RT-AC88U loses WAN connection