Bad Speeds with PASV mode?

[r.haehnlein]

Hello everyone,

I somehow have a problem that doesn't sound logical to me at all and I can't get any further with it, so I would like to ask for your help please.

When I use FlashFXP (or any other FTP Client for that matter) with ACTIVE Mode on, I get great download speeds up to 19 mb/s. But as soon as I switch to PASV Mode (because some servers don't work with active mode and produce error logs like the one below) my download speed seems to be capped at 7,79 mb/s.

200 PORT command successful
MLSD
PORT failed, try PASV mode!

I tried and confirmed this with several 10 Gbit Servers... with PASV Mode I can't get higher than 7,79 mb/s, not even for a second.

I thought about some wrong TCP RWIN Settings first and tried different settings.... and I tested all possible TCP Buffer sizes in the FlashFXP client as well... but nothing had a positive effect at all :/

Also I noticed that this only happens on Windows 7 x64 (Ultimate), on Windows 8.1 Pro (which I run on a different SSD) I reach 19 mb/s with PASV Mode, too. However I still wanna use Windows 7 as my main OS, so I would love to get this fixed and solved.

Looking forward to get any help/input. Thanks in advance!

Kind regards,
Ralf

[r.haehnlein]

Okay can be closed, was a problem with my Windows 7 Installation.

/edit:

netsh interface tcp set global autotuningl=normal

solved the problem for me

[X3]

Thank you for providing the solution attached, it may help others that come across same question.