DSL slower behind your firewall than when attached to the DSL modem?

Great tip from the folks at Calyptix:

On DSL connections, if you are experiencing slow Web browsing, or certain Websites and downloads not loading across multiple computers on your network, you might need to change your firewall’s MTU (Maximum Transmission Unit, or largest packet size that can be transmitted) value from the default of 1500 (default on most firewalls) to either 1452 or 1492.

You can check with your ISP for their recommended setting, but a simple way to check is to run a speed test from behind your firewall using each of the three settings (1500, 1492, and 1452) and take the one that reads the highest over a couple tries. For example, with Actiontec DSL modems, Calyptix and SonicWALL firewalls, and Qwest in Seattle, Washington, 1452 is working the best from what I’ve personally seen so far. If you are on Qwest, use http://speedtest.qwest.net/ (always use your ISP’s test if they have one for the best accuracy).

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