Is that really a relevant question? A full-stack title usually means web front-end, mobile, web back-end (or API), and database. Its a generalist title. You work mostly with HTTP, but even then an API framework may hide that.
If you're deploying to a PaaS you may never care about or notice lower layers. If not, your team may have a specialist (DevOps, platform engineer, network engineer) who manages network configuration, DNS, load balancer, connection pooling, firewalls, VPN, and other details.
The “stack” in full-stack engineering used to refer to the software stack, not the network stack.
The old-school eponymous LAMP stack used to be Linux, Angular, MySQL, and PHP. You wouldn’t necessarily have had to have known the OSI model to be proficient in those technologies.
What's your point? Titles rarely match competences and responsibilities.