Which layer of the osi model is most directly impacted when an internet services provider is found to be blocking udp traffic from a source host?

The Open Systems Interconnection Reference Model is an abstract description for layered communications and computer network protocol design. In its most basic form, it divides network architecture into seven layers which, from top to bottom, are the Application, Presentation, Session, Transport, Network, Data Link, and Physical Layers. A layer is a collection of conceptually similar functions that provide services to the layer above it and receives service from the layer below it.