Intermittant internet connection on Verizon DSL thru RT311

We've got an odd one here.. There's 20 odd Windows 2000 machines on a 10/100 network.  Internet service comes in over DSL into a Netgear RT311, from there to a netgear switch, and out to the machines.  There are some other machines in a nearby office, connected by a wireless bridge.  

At any given moment, there is one machine on this network that has "the bug" ie:  at seemingly random intervals, it looses it's connection to the internet, while retaining intranet connectivity (shared drives, printers, etc)  This is evidinced by IM clients loosing uplink and then like minutes later logging back in, and interrupted web navigation +m page loads.
This symptom has jumped from machine to machine, it's on machine #3 as we speak.  

Possibly useful additional info:
All machines are served DHCP from the RT311, it has been restarted and resetup from scratch.
FTP, e-mail connections also do not work during these intermittant outtages.
The RT311 router is configured to send out a dynamic ip range from up to .85, as there are some servers (print, file, DBS) with static IP's below that.
The machine that is experiencing the bug, appears normal ie: shows complete info via Ipconfig as having a DNS connection etc.  
Doing a release/renew seems to help, but the outtages only last about a minute or so, so it could just be "the bug" unfuckerating itself.
Any thoughts? Questions? Avenues of investigation?
Thanks in advance.
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infotraderConnect With a Mentor Commented:
Because DSL often uses the PPoE authentication, it is usually a good practice to change the MaximumMTU size from the default (1500) to 1492 (some even recommend 1460).  The reason for that is that PPoE tags on another 8bit for authentication purposes, which bumps up your typical 1500 to 1508.  When that happens, your workstations would either quit because it can't handle it, or sometimes would just result in numerous packet losses.

- Info
Fatal_ExceptionConnect With a Mentor Commented:
We discuss MTU size a lot in this section...  As info notes, it is a problem when dealing with DSL especially..  Here is a link for the changing of MTU for your machines..

I would also go to your router and ck its config..   I believe that you can set the MTU on these statically..

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