I’m using Linksys WRT54GL as my home WiFi controller – connecting 3 desktops and 4 mobile devices (2 laptops, a Tablet PC and a Pocket PC) to the Internet and between each other.
Recently, a new housemate has moved in – an old friend of mine. He’s a heavy P2P user, downloading hundreds of files at the same time thorugh eMule. I, as an old eMule user, have configured his client to be perfectly fit to our broadband connection. However, we started seeing huge lags on other machines. I cut down the upload speed on eMule, but – surprisingly – it did not help. Neither did cutting down the total connection limit (AKA hard limit).
I sat down and started thinking. There must be a limit somewhere, but it’s not that (like with El Cheapo routers) it’s just getting too many packets and cannot handle them, because cutting down the transfer speed didn’t help. So – what else is there in router that can overflow? NAT table! Could it be?
I googled a bit and it turned out that WRT54GL has very small NAT table – like 512 entries. It seemed it’s a bit too small for 3 people actively using the Internet, plus eMule running in the background. I found a third party firmware for the router – Tarifa. It’s open source, free, easy to install and has the same configuration GUI as the original Linksys firmware.
I tried it and – voila – everything works smooth now. I can change the upload speed of eMule as I wish and it won’t block my network. So, if you have similar problems, give the Tarifa software a try.