Part of macOS
symptomsd…Network health
○ Leave it
Watches network connections and notices problems.
What it is
Tracks how apps use the network and helps macOS spot and recover from connection trouble.
If you stop it
macOS starts it again straight away. Leave it.
The verdict
○ Leave it. Part of macOS, or something that starts again by itself. You never need to close these.
In Activity Monitor
symptomsd…
… means any name that starts this way.
From Procession’s guide, in the words the app shows.