[Bug 525049] Re: 3G download speed is very slow compared to Hardy on elderly PIII computers or Microsoft Windows OSs

[Timo Jyrinki]

I'm affected as well. I narrowed the problem down to TCP connections.
Indeed two (or more) TCP connections each get 15-20kB/s in the Sonera
mobile network, but no more. UDP on the other hand apparently flows
without problems, so somehow Sonera hardware/software manages to slow
down all TCP connections.

I found out that:
echo 0 | sudo tee /proc/sys/net/ipv4/tcp_window_scaling

...ie. disabling TCP window scaling removes the problem with possible
side-effects (nothing that severe compared to the benefits so far it
seems, though). Another person I helped taking that into use reported
that speedtest results rose from ca. 140kbps to 1,3Mbps. I can myself
only test that indeed I'm now getting full 384kbit/s my subscription
allows.

No other operators are affected, but somehow Sonera's hw/sw in its
mobile network is intolerably incompatible with Linux at the moment. I'm
not sure if Linux could do some detection or something better when it
comes to TCP window scaling in that environment.

-- 
3G download speed is very slow compared to Hardy on elderly PIII computers or Microsoft Windows OSs
https://bugs.launchpad.net/bugs/525049
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