First off, here's the network architecture: ISP (untrusted) router (NAT) | OpenWRT (trusted) router (NAT) ... wireless device | Cisco (unmanaged) switch-----------+ | | Netgear (unmanaged) switch wired device | Debian server
If I ping the Debian server from OpenWRT, the wireless device, or the wired device I get 25%-30% packet loss *unless* I am pinging an external IP from the Debian server at the same time, at which point the packet loss goes below 1%. I have no explanation for this. But wait, it's even weirder than that. Pinging from one wireless device to another wireless device *also* shows significant (~20%) packet loss unless the Debian server is pinging an external IP. Note that pinging an external IP from a wired or wireless device doesn't seem to have any impact. I suspect that something bad is happening at the Ethernet layer that I'm just not seeing, but I don't know where it's coming from or what I'm looking for. I've used tcpdump from the places where I can (OpenWRT, Debian server, wired and wireless devices) and looked at it in Wireshark, but nothing jumps out at me. There is a pretty strong chance that this isn't coming from the Debian server at all, but a ping from it has some magical effect on the network. I've been fighting this for days and I'm just at a loss. I'd very much appreciate any advice or options to try. Thanks, --Gregory