Tools to diagnose bottlenecks on a home network

I am looking for some simple tools to identify network bottlenecks on my home network.

Here's the situation I am trying to debug

I have a 2018 google wifi mesh and have encountered a peak transfer rate of 5MB/s when transferring files from my laptop to a Synology DS418play NAS that is 2 mesh hops away.

Each of the devices and network hops should be capable of much more and I can't tell what the bottleneck is.

FWIW

- The mesh reports a connection speed of 455Mbps with my laptop

- I can read from the SD card on my laptop at about 70MB/s

- The Synology drive has a Raid 5 config with 4 5400 Western Digital Red Drives