Does plex use bandwidth when on the same machine?

Sorry kind of noob question here, but:

I like to use plex to watch videos on my own computer because of the lightweight browser interface and some of it’s other features.

However, using a network monitor I am noticing that it is using a lot of upload speed. So I have two questions:

  1. Why is it using any kind of networking when it is on the same machine, is this normal?

  2. Is this using my actual internet bandwith? Or just my router/modems local “bandwith”?

Plex is built as a ‘server’. Every communication it does uses networking infrastructure.

But there could be an issue with your router which may cause this behaviour.
To verify this, do the following:
Settings - Server - Network - ‘Secure Connections’ = “Disabled”
afterwards, restart both Plex server and your web browser.

Then go to Settings - Web - ‘Allow Fallback to Insecure Connections’ = “Always”
then reload the ‘web page’ with F5

Then repeat the playback test and keep an eye on your network monitor.
How does it compare?