Internet connection performance issues - Netvanta 2300 v2

[#1]

Hi all -

I'm probably missing something obvious here, so I'll wear the dunce hat as I ask the community for some ideas/help. I'm having a rather serious fight with our ISP over speeds/performance on our connection, and am at a point where I've run out of things to try. We are consistently getting between 1-2Mb/sec bandwidth coming to us, and 8-10Mb/sec bandwidth going out, regardless of testing host (I'm using a couple bandwidth testers, including Speedtest.net, and one that our cable company operates on their own network). Under normal circumstances, I'd say our cable company is oversubscribed, and that has been my argument with them. Today, they (finally -- after 3 weeks of phone calls, and an escalation to Tier 4 support) sent a tech out to run speedtest.net on his laptop connected straight to the cable modem. Here's where it gets interesting:

1) Using a dynamically assigned IP address (DHCP), he pulls 45-50Mb/sec download, 15-20Mb/sec upload, on a number of sites, including the cable company's own server. There are of course a few that he hits that just stink, but I'm stunned at the performance.

2) I ask him to assign his laptop one of my static IP addresses, and see if its a routing issue. He tries, but he gets no Internet using our static IP address and gateway. We reset the modem, call in, the whole 9 yards.

3) We hook my Netvanta back up, and go into my office and pull from the same sites. Poor performance again.

4) I reconfigure the Netvanta for DHCP on the public interface, and click "apply". It picks up a DHCP lease on the ISP's network, and proceeds to run with it. Start speedtest... Initially, the downstream performance is improved (in the 5-6Mb/sec range), but then falls back off to 1Mb/sec.

The tech goes on his merry way to report his findings to his boss, who I'm sure will say its our equipment. I'm a bit frustrated that he couldn't demonstrate the same performance using our static assignment (which is in a completely different IP block), but that aside, I plan on playing with it tonight after everyone else goes home and I can have the router to myself. I should also point out that my "available bandwidth" does not change even at 10pm when no one else is in the building. I have even plugged a laptop directly into the Netvanta private port, and the bandwidth is still yuck.

I realize I've got multiple folks on this router/firewall, so I'm not expecting to see 50Mb/sec down when the office is open, but if we were getting half of the performance the tech's laptop said we have, we wouldn't be getting timeouts on our hosted exchange connections, .Net applications, and remote transfers. The Netvanta web interface responds smoothly, and while I can't see a performance meter anywhere, I don't see any packet errors on any of the interfaces.

Our ISP (a cable company) has an Arris WBM750A cable modem on our premises, which supplies our network with public Internet. The cable modem is connected to our Netvanta 2300 on the Public IP port (eth 0/1), and the Netvanta has been programmed with a static block of IP addresses (we only use 1, but we have 5 as part of our package from the ISP). I have eth 0/1 set at 100Mbps/Half, as the performance DROPS to 1Mb/1Mb on 100M/Full, and I start seeing packet errors. The modem itself was replaced last August after complaints about performance.

Is the Netvanta 2300 just not capable of these kinds of speeds? Am I missing something obvious here?

A "cleaned to protect the innocent" config file from my 2300 is below. Any suggestions or "I've seen this before" replies are greatly appreciated. Thanks!