Does a DDoS Attack affect the internet connection apart from the service it's attacking?

Question

Lately I've been experiencing some crashes related to my internet connection, I'm on the process of pin-pointing what is causing the issue and one of those possible causes might be a DDoS attack, mostly because of the symptoms resemble what a DDoS attack does.

However, something that I don't quite understand is in how a DDoS attack affect the internet connection where the server is running.

For example, let's say a DDoS attack is doing constant POST requests to a website and the web server can't handle all those requests, thus it slows down and/or crashes.

However, does that attack also affect the internet connection of rest of devices connected to that network? ie: computers that are using the same internet connection as the server that do not recieve these post request, thus they do not slow down or crash.

Can a DDoS attack affect the internet connection of other devices and prevent them from browsing the internet? Can a DDoS attack consume all the bandwith of a network that makes the rest of the devices not being able to use the internet?

Answer 1

If the DDoS is big enough any link can be saturated. Every request takes up a bit of bandwidth (and possibly other resources like CPU on a firewall), and no resource is infinite. So yes, this is possible, but to make sure you would need more metrics and diagnostics.