[clue-tech] Network Woes

[Todd A. Gibson]

Hello,
Hopefully someone can push me in the right direction.

Setup: Everything in the house is connected to a switch.  A DSL modem
and a server have fixed LAN IP addresses.  The other computers receive
DHCP services from the server (DHCP server services are turned off on
the DSL modem).

Symptoms:
I lose the ability to make new connections through the DSL modem
(either into or out of my server).  New connections include Web
queries, ssh, telnet, ftp, etc.  Also during this time some LAN
traffic is hamstrung.

Examples:
local_one$ ping local_two #works OK
local_one$ ssh local_two # 15-30 second delay before prompted for password
local_one$ ssh 192.168.1.246 # prompted for password immediately

If I put local_two's IP into local_one's /etc/hosts then "ssh
local_two" works immediately as in the direct use of IP above.

Finally, although new connections die at the DSL modem, existing ones
seem to be fine.  For example, currently running ssh sessions into
my network stay up even though I can't create new ssh sessions.

If I reboot my DSL modem, all of these problems go away for almost
exactly one hour, then the DSL freezes up again, etc.  So here are my
questions:
1) Do ping and ssh resolve names differently?
2) The above implies that the name resolution is passing through the
DSL modem, even in the case of locally resolved names.  Is this
normal?  Any particular goodies in bind or elsewhere I can look at to
address this?  I touch these services once a year at most so I always
dread having to relearn the config files, etc.
3) Anyone else experience something similar with a Zoom X5 DSL modem?
Is there any reason to suspect something other than a hardware failure
or a firmware bug?  The most unnerving part is that the problem always
reoccurs exactly one hour after modem reboot.  This problem has been a
minor nuisance since I installed the modem a couple years ago and has
accelerated into this hourly event in just the last few days.

Thanks for any wisdom you can impart,
-TAG
Todd A. Gibson