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 From:  Edmund Lian <edmund underscore lian at juscom dot com>
 To:  Claude Morin <klodefactor at gmail dot com>
 Cc:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] Sporadic routing failure affecting only Windows machines
 Date:  Tue, 15 Mar 2005 18:43:34 +0800
On Mar 15, 2005, at 15:09, Claude Morin wrote:

> Not to keep beating the same drum (as in some of my other posts) but
> this may be an MTU issue.

It was an MTU issue. After putting a packet sniffer on a Windows host, 
I saw that the syn and ack packets to and from the FreeBSD server were 
getting through, but then everything else was lost.

After changing the max MTU on a Windows host to 576, everything began 
working again. I would have thought that PMTU discovery would take care 
of MTU problems.

As for the sporadic outages--I'm guessing that one or more routers we 
connect through (ADSL line with forced periodic logouts) is not 
configured properly, so that when we get a bum router, the Windows 
hosts gag. As to why the Macs were unaffected, I guess one must put it 
down to Microsoft's stack being deficient/less robust as compared to 

Thanks to everybody for their thoughtful suggestions, I really 
appreciated the help.