TCP Window Scaling issue when downloading files

[skinford]

We recently upgraded our PaloAlto firewall and are having issues downloading files on Macs. Files start out fast and then suddenly decrease on the clock to "Days" instead of "Minutes".

Our security team says that it has to do with TCP Window Scaling. They say that TCP Window Scaling, is off by default on a Windows system, but on by default on a Mac.

Is there a way to disable TCP Window scaling on a Mac, via a terminal command that anyone knows of?

Thank you all in advance!

[TobiasII]

Hi, I recently encountered this issue in my environment also. I disabled TCP Window scaling on mac by using sysctl. which will set tcp parameter to '0' and disable window scaling.

sudo sysctl -w net.inet.tcp.rfc1323=0 

Then, you can verify parameter changes with - It should return 0.

sudo sysctl net.inet.tcp.rfc1323