Networking/Gateway Issue + Pfsense

[Blue Knight]

Can anyone tell me what would cause a computer to intermittently not be able to access the internet, but can ping the gateway?

I have a dual-wan PFsense box. One computer is working fine, but another computer right next to it will sometimes have its internet die. I can ping the pfsense box (gateway), but nothing past that. No DNS servers, internet gateways - nothing.

Here's the kicker - there are wireless routers also on hooked up to the networking and routed through the dual-wan router. If I switch the computer to the wireless network, it works fine.

So, i tried testing the port - and switched the cat cable to a laptop. Same issue. I can ping the gateway, but can't get out to the internet - sometimes. Wait 5 minutes and the internet will work, but still intermittently.

I thought I was overloading the pfsense box, but it's at about 5% CPU usage with 70% memory free. There are about 50 clients on this network simultaneously. (box is a 1ghz PIII with 512mb RAM). Internet usage is primarily for gmail.

Edit: I can also tell you that the internet connections themselves are stable and aren't the cause of the internet issue.

 

[Shockey]

both these computer on the same lan?

 

[Blue Knight]

Some more to add: Would a network loop cause something like this?

Just asking - I talked to the "admin" here...and there were a bunch of daisy chained airports in front of these computers. We removed a few out of the loop and reran the network.

*sigh* work for non-profits is always interesting....
Edit: to answer above, yes, they're on the same LAN and subnet - at least I think. they're right next to each other, so hopefully they're connected to the same switch.