advanced security

Comcast has recently begun blocking an IBM subdomain: dhe.ibm.com.   I spent 2 hours on the phone with support last night.   No joy.  It acts like a DNS problem, but I wondered if Advanced Security might be blocking it.  So I went to turn it off and I can't see how.  When I get to the Advanced Security tab, there are no options to turn it on or off.  All it is says is "You're protected."  and "No action needed."

How do I turn Advanced Security off to see if that's what's blocking the subdomain?

Thanks.