SMB stuttering, how can I see actual network transfer speeds on LibreElec?

I'm trying to troubleshoot stuttering with SMB files. I'm thinking maybe, somehow, SMB networking is slow between Pi and server (because it's gigabit wire speed from my Linux machine to the Linux SMB server, and it's 100 mbits from my Linux machine to the Pi using scp)

As a test, I'm copying a large file from the SMB share onto LE's internal storage using the file explorer.

But how can I see the actual transfer speed in real time? I tried `netstat -e` over ssh but it doesn't show that information. And I can't install any other Linux package because of LE's nature.

My router doesn't show SMB traffic in its speed graphs for some reason.

Thanks. LAN speeds and internet speeds are fine, they completely saturate the 100 mbit port on the Pi. The problem seems to be with SMB from the Pi, because SMB from my desktop client gets wire speed (gigabit). But SMB from the server to the Pi is what seems to be slow to a crawl, although I don't know how to actually measure it.

I tried copying a file from the SMB share to the Pi's sd card, timing it, and then dividing by the amount of data transferred. I got 4 MiB/s which is very low, but I don't know how much of that is a function of the sd card's write speeds.