Disabling TCP windows scaling indeed did the trick. I would recommend disabling this by default since it seems to cause these kinds of obscure bugs with various configurations. Even if it's not Ubuntu's fault, we can't fix every server out there, or hope they ever will get fixed anyway.
Disabling TCP windows scaling indeed did the trick. I would recommend disabling this by default since it seems to cause these kinds of obscure bugs with various configurations. Even if it's not Ubuntu's fault, we can't fix every server out there, or hope they ever will get fixed anyway.
Thanks for your help!