FVS-318gv2 wan port would not connect with Arris SB6141 modem

My FVS318Gv2 firewall was working fine with an SB6141 modem until yesterday. All of my computers were off for about five hours when I noticed the wan ports activity leds flashing continuously indicating that the router was communicating with the modem. No other ports were showing any sign of activity. When I resumed work after the five hour off interval the connection between the FVS318Gv2 wan port and the modem was down. I reset the modem, the router several times but could not get the wan port to connect. I opened the routers web interface and tried to activate the port there but could not do so. I had previously saved the configuration to a file, so I loaded that back into the unit but that did not help. I then did a hard reset of the device which gave me the correct default IP address 192.168.1.1 for the gateway but I could not log into the router through the web portal. Finally, after calling support and going through the above mentioned steps again Netgear support decided to send me a new unit which I should receive in a day or two. Does anyone have an idea what could have happened here? We have had DoS attacks before but the unit was never permanently damaged. Any thoughts on this would be appreciated. The latest firware was loaded into the unit.