Yes, blocking access to that IP would cause such a problem. That is one of the IPs for our sync servers where all content sites are downloaded from. You can try enabling gather via HTTPS to see if that helps avoid issues with your firewall: https://www.ibm.com/support/knowledgecenter/en/SSQL82_9.5.0/com.ibm.bigfix.doc/Platform/Config/c_https_gathering.html