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I am using Windows 7 RTM, and things are running smoothly for the most part. My Windows 7 installation is the default, out of the box configuration.

I am using the standard TFTP utility available with Windows 7. When I attempt to upload a 3 kb text file to our internal TFTP server, it always time's out. However, TFTP'ing the same file, on XP (from the same network port --- different laptop, but same model) it works perfectly.

Is anyone aware of any default configuration on Windows 7 (or even) Vista that could cause this?

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There is a warning at the DD-WRT TFTP-Flash page that might be useful.

Recommendations - In order to catch the narrow window for TFTP flash, you should use platforms with simple TCP/IP implementations that don't have CTCP implemented: WinXP or Linux are reported to work, but some are reporting significant problems with Vista, Windows 7 or Windows 2008.

Can you consider using the FTP client?
you would need a FTP server rather than a TFTP server at the other end.

According the the Wikipedia page, the following is supposed to disable CTCP,

netsh interface tcp set global congestionprovider=none

However, what I fail to understand is -- TFTP uses UDP rather than TCP,
So, I don't get how the CTCP problem is related to TFTP.

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up vote 0 down vote accepted

It seems that the issue may be with the network card driver. I'll wait until an official Windows 7 driver is released for my Broadcom NetXtreme Gigabit NIC.

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Turned out it was my 3rd party firewall disabling this traffic. Kind of a dumb mistake on my part, but I wanted to post the root cause here in case someone runs into the same problem/oversight. – Mick Dec 6 '09 at 18:58

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