Description
The URL filter is configured to allow only a specific website which in the example is youtube.com. All other websites would be blocked as the filter is configured with a * and type as 'wildcard'.
The article highlights that if a specific website is allowed by using URL filter, the websites may load correctly but the contents of that website may not work correctly.
The access to the website itself works as in the image below for youtube.com but as can be seen, it may be difficult to load the contents of that specific website which in this case would be videos and images etc.
These are usually loaded from other sites, content delivery networks (CDN), so different FQDNs that are as above configured, blocked.
Solution
Some web sites have inside contents on the other sites such as videos on Youtube are in the domain googlevideo.com.
Try to access the web site then check on web filter log (WEBGUI -> Log & Report -> Web Filter) to see which URLs were blocked then allow them.
Also check on developer tools on web browser to see which sites are required when desired website is accessed.
In this example, allow other URLs as below screenshot (tested on Sep 2020) to make access www.youtube.com and see contents as expected. \
Note that if there is some change on the destination website such as domain name of the content site was changed, correct URL filter again is necessary.
Note.
- Refer to this KB for more detail on three types of URL filter https://kb.fortinet.com/kb/documentLink.do?externalID=FD45628
- Enable deep SSL inspection on the policy to make URL filter work correctly on HTTPS website
https://kb.fortinet.com/kb/documentLink.do?externalID=FD46282
https://docs.fortinet.com/document/fortigate/6.4.2/administration-guide/122078/deep-inspection
