Yes It is the case. (NTLM)
The problem is coming from NTLM : IIS with Firefox,Safari
I tried many things to solve the issue in vain.
Also this command doesn't fix the problem.
appcmd.exe set config -section:system.webServer/security/authentication/windowsAuthentication /-"providers.[value='NTLM']" /commit:apphost
With Firefox I can set Automatic NTLM Authentication but I need a solution in IIS for all browsers.
I am missing some thing in IIS config (Providers, ASP, I don't know really)