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We finally decided to upgrade to a DSL (I know, not much of an upgrade, but nothing else is really available in our area) and I set it up and tested it through a laptop connected right to the modem. We had our full speed. However, when I connect it through the Sonicwall, out speed drops DRASTICALLY, well over 50%.

I have the modem in bridge mode, and can not understand why it is bottlenecking.

Any help on this issue is much appreciated.

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What's the link configuration between the SonicWall and the modem? Full Duplex\100Mbps? – joeqwerty Sep 13 '10 at 15:16
Yeah, that's what we have running. – AgainstClint Sep 13 '10 at 16:07
Are both sides hard coded to Full Duplex\100Mbps? Do both ends support Full Duplex\100Mbps? Any collision indicators on either end? – joeqwerty Sep 13 '10 at 16:28
Both ends are hard coded to Full Duplex\100Mbps, and are both supported. – AgainstClint Sep 13 '10 at 19:23
up vote 1 down vote accepted

We found the solution. It turns out, our Sonicwall firewall set the DSL line as a backup to the main line. It was directing all traffic to the main, slower line and keeping the faster one as just back up.

A quick switch in the settings and it was up and running.

Goes to show, always check the simple stuff first.

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Mismatched MTU? Try lowering MTU on Sonicwall interface and see if it helps... Ask your ISP about MTU used on their lines.

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Yeah, I tried 1492 (which seems to be the Verizon default) with no change in speed. We should be getting ~3Mb/s, but we are only getting 700 Kb/s. – AgainstClint Sep 13 '10 at 15:53

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