I have a pretty underutilized Ethernet LAN at home -- basically I am usually the only one using it, everybody else is doing WiFi.
A strange thing that I have noticed is that I have inconsistent large file copy speed from my PC (Windows 10 Pro) to my NAS (Synology DS214+).
At times it will be around ~80-90MB/s and stay that way, but quite often it will be around 40MB/s and not raise above it.
Rarely it will also start at ~80 and drop to ~40 early during transfer.
I am usually copying from a SATA SDD, and I don't have any background (eg. torrent) transfers during the copy time.
The connection is: PC -> [gigabit switch ] -> [ router ] -> NAS
What have I checked:
- Background apps/file transfer on PC -- practically never present
- Other LAN traffic hoggers -- use WIFI, shouldn't affect Ethernet? Beside nobody is even streaming video or downloading anything during those times that I copy
- Some tasks on Synology? Possible, but I generally have scheduled things to update during night
What other things I should check to eliminate issues?