[TriLUG] TWC BC periodic internet disconnections

[Bill Farrow]

Hi,
I'm struggling with the customer support people at TWC Business Class
over periodic disconnects.  Every 30 hours or so the internet
connection stops working, sometimes for a minute or two, but other
times the outage lasts for several hours until someone gets on site to
power cycle the modem.  One of these outages happened during a VOIP
conference call with a customer.

We are using a TWC BC provided Ubee DDW3611 modem (details below), and
we have a static IP.  Connected to the modem is an Ubuntu 12.04 server
running Zentyal 3.0 (Small Business Server).  This Linux server is
configured with a static IP on the WAN and  uses a fairly complex
iptables firewall config.  The Ubee modem is configured with a static
IP, and the server uses that as the gateway IP.

I am now monitoring this from home using a bash script that pings
several IP addresses every minute.  When the TWC BC internet
disconnects, I the script is unable to ping the modem's static IP or
the linux servers static IP.

After talking with TWC BC support, they added the modem to their
"Watch List" for a 72 hour period.  During that time we lost internet
again and called support.  They claimed there was nothing wrong with
the modem, and it must be our equipment and we should power cycle it.
I'm not convinced, so I am asking here - have I missed something on my
Linux server that could be causing this outage, or is it really a TWC
BC problem ?



Cable Modem : DOCSIS 3.0 Compliant
MAC Address : C4:17:FE:xx:xx:xx
Serial Number : BC11U2900xxxx
Boot Code Version : 10.1.2
Software Version : 8.6.2009
Hardware Version : 4.31
CA Key : Installed

Bill