NTLM authentication issue with POSTs in SWG

Thanks for your quick response! The system is running 11.6.0 build 0.0.401-Final. I've tried with different browsers (Firefox, Chrome, and I think I also tried IE) but it didn't seem to be related with the browser, so I focused into trying to understand the SWG behavior. The fact that it is not always sending the NTLM authentication request after the same number of bytes makes me think is a timing issue (after x ms it sends the request, which might be related with the time it takes to do whatever). I'll upload the required information tomorrow morning (BST). Thanks!