Access to some web pages are impossible

Hello,

We are suffering the following issue:

We have a Fortigate 100E and was working ok until some users reporting us that they can't access to a web of a bank, we did everything, tried with DNS of fortigate and google and others, even let the navegation without inspection or any shield and nothing worked to access to the page. Finally we created a Policy Route to give access to the web site and this worked but with the pass of the days it has growing the amount of web sites with issue to access. We thought that adding the sites to the Policy Routes it was enought but isn't. We have no access for example to Bank of America in no way. Its like if simply that's sites doesn't exist to the fortigate and every day added one more to that issue.

Thanks in advance for your support.