The “No Internet” Ruleset is a built-in Rule Set that is designed to allow no DNS queries to resolve when it is applied, effectively blocking all traffic that requires DNS. Furthermore, DNS-less traffic is disallowed.
When the “No Internet” Rule Set is used in a schedule, it works as expected in that blocking is effective as per your schedule for all new requests. Pre-existing TCP sessions prior to the scheduled change, such as a Steam game may or may not be disconnected according to this reference:
|Transition to "No Internet"||Blocked by DNS||Pre-existing TCP connection termination|
|pfSense 2.3, 2.4||Supported||Not Supported (support coming soon)|