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Tip for slow routers, to enhance performance


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I've had serious problems with wireless routers and uTorrent for a while now. Even though port forwarding works, and I do have no connection problems, my router seemed to be very sluggish in its control panel and had bad performance. This happened with a 3COM 3CRWER100-75 and a Sofa@Ware 500W (which is a 500$ wireless router, that has a control panel that actually shows memory and CPU usage). It got to a point that my router was out of memory and I actually lost connection to it - an actual DDoS attack on myself! :)

I noticed on my 500W that the integrated firewall was having a hard time, dropping many many packets. Then, I noticed that uTorrent sends out packets (outgoing connections...) on random ports (as per the Winsock spec), and the response is expected on the same port. Incoming connections are on the main, configured uTorrent port. However, my router's firewall was not remembering outgoing UDP packets, and thus did not remember to expect responses on these random ports. The result - it dropped many, many packets, hogged the router's CPU and caused bad performance altogether.

The solution? I port-forwarded a range of 10 ports (3 or 4 should be enough for just about anything, however) on my router, and set uTorrent's advanced options net.outgoing_port and net.outgoing_max_port:

net.outgoing_port is the bottom of the port range

net.outgoing_max_port is the top of the port range

The result? the firewall is no longer swamped, the router is no longer sluggish, speeds are up.

Possible downside: my ISP might detect the surge of traffic on this single port range and shape the traffic, killing performance. I'll have to wait and see what happens.

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