Accessing Yahoo with browsers

[duser]

Hi

I actually use fortiguard 300d to protect my network.

I noticed that my machines can’t sometimes access to some authorized websites; like yahoo.

Pinging yahoo works all the time.

But accessing with firefox (56, the latest) or Internet Explorer, doesn’t work every time.

Baidu browser is the only browser that can access all the time without any problems.

Application control, DNS filter, and web filter are enabled for all machine.

I created a new IPv4 policy for my own machine without any filter to see if I can get access to yahoo, but It doesn’t work.

I thought that it may be related to Certification, I installed all available certifications:

Fortinet_CA, Fortinet_CA_SSL, Fortinet_CA_Untrusted.

But it doesn’t resolve the problem.

Thank you