I have a moderately complex home network that serves me well for internet connectivity, but has a major problem when I try to transfer files within the network. I am a novice when it comes to networking, but I learn quickly, so hopefully I can learn from the pros on this forum. I set up this network piecemeal as my needs changed over the past few years, so it may not be the cleanest design, but I hope I can modify it a bit to get it working without doing a major redesign/hardware upgrade.
First I'll describe the network basically. Please ask any questions necessary to clarify important points necessary to fix my issue.
[DSL Modem]--ethernet--[Belkin Router A]--ethernet--[EnGenius EOC-5610 AP]--3.5 miles wireless bridge--[EnGenius EOC-5610 AP]--ethernet--[Belkin Router B]--wireless repeater bridge--[Belkin Router C]
All the hardware is off the shelf, with the exception of Router C which has been modified by DD.WRT to enable the wireless repeater bridge feature. But if you like you can ignore the connection to Router C altogether, because the issue was present even before I added it to the network.
The 3.5 mile wireless bridge is a slow (but stable and reliable) link in the chain and operates at just 2.5 Mbps, but this is normally not an issue because I rarely transfer large files across this bridge, and my internet is only 1.5 Mbps.
Ok, so the problem: Normally when transferring small amounts of data around the network, or just using the internet, I notice no issues. But when I try to transfer a large file between 2 computers on Router B (or C) it transfers very slowly...somewhere in the area of 7 Mbps...far short of the 56 Mbps wireless or 100 Mbps wired speeds I should be seeing. Also, while the file is transferring, my 3.5 mile wireless bridge is filled with traffic. So much so that the internet becomes unusable on computers connected to Routers B & C during the transfer.
So my best theory is that some sort of data is traveling all the way back to Router A during the transfer, even though Router A should have nothing to do with data traveling between 2 computers connected to Router B. Clearly not all the data is making the round trip as the link is only good for 2.5 Mbps and yet the transfer runs at around 7 Mbps, so if all the data were making a round trip through Router A I'd be seeing around 1.25 Mbps. But something is clogging my long distance bridge during the transfer, and waiting for this data to make the round trip is slowing the overall transfer as well.
Well that's the best I can explain it for now. Please ask for any more details you need. I realize there are a lot of variables here, but I'm hoping someone has seen something like this before and can point me in the right direction. My data clearly isn't being routed properly, but I can't figure out why. Thanks much for any advice!