"Access Denied" Message on certain websites

[iowa]

I've been getting this on certain websites. I'm not sure what's causing it, but it is something on my network. Running a traceroute doesn't seem to show anything wrong, as it finds its way there with no problem.
I'm not running squid (don't even have it installed!). Rebooting pfsense seems to fix it though.
I also recently updated it.

2.4.0-RELEASE (amd64) 
built on Tue Oct 10 06:43:01 CDT 2017 
FreeBSD 11.1-RELEASE-p1 

Any ideas on what's wrong?

EDIT1: Updated to latest version, rebooted, still having the same issue.

	2.4.2-RELEASE-p1 (amd64) 
built on Tue Dec 12 13:45:26 CST 2017 
FreeBSD 11.1-RELEASE-p6 

[jamesonp]

The looks like an Akamai CDN error page.

https://community.akamai.com/community/cloud-security/blog/2016/04/07/why-is-akamai-blocking-me