Are you in an ADSL or VDSL area? If VDSL, you will have to put the Actiontec modem in bridge mode and connect it to the WAN port on the Netgear router.
What WAN port? The Netgear D6200 is an RG with a phone port, a USB port, and four LAN ports.
As per the Netgear product page:
One (1) USB 2.0 port One (1) ADSL2+ port IEEE® 802.11 b/g/n 2.4 GHz IEEE 802.11 a/n/ac 5.0 GHz Five (5) 10/100/1000 (1 WAN and 4 LAN) Gigabit Ethernet ports with auto-sensing technology
