Suggest staying away from the Billion 8800NXL. VDSL modem is rock solid. WiFi on the other hand is hit or miss. Some users are fine, and others like me have serious issues.
Got a Billion 8800 but i just use it as a modem the Asus RT-66AC does the DHCP and Wifi.
Have the Zxyel at the office, its not bad, but not as good as the Billion. Also used it as a modem only.