Extremely slow transfer speeds on gigabit LAN

Silverseas · October 18, 2019

Hello,
I've got an issue that has me stumped. I've recently set up my gigabit LAN and am getting significantly slower speeds than I'd expect. I have a desktop PC connected to a gigabit switch, connected to a laptop. All devices have gigabit ports, updated drivers, latest windows version etc. I'm transferring between two SSDs with read/write speeds of about 400MB/s.
When I transfer a test file I generated in the command prompt I get a steady 110MB/s speed. Great. However, when I transfer a single large MPV, MK4, MOV etc. file I get about 30MB/s tops after the buffer is full.
Steps taken so far: Large send offload IPv4 disabled. iperf3 showed speeds between desktop and laptop at about 800Mb/s, entered "netsh interface tcp set global autotuning=disabled" into command prompt, disabled all antivirus and firewall settings, complete factory reset of my PC to see if I had any weird programs causing issues.
If my test file wasn't working as intended I'd be less frustrated, but because it is I know there's no problems with any of my hardware and it's just something to do with windows. I've talked to Microsoft support but that was less than helpful.
Anyone have any ideas what may be causing this?

Radium_Angel · October 18, 2019

19 minutes ago, Silverseas said:

Anyone have any ideas what may be causing this?

Possibly. What kind of device are you copying the file to? An SSD, HD, flash stick? That device's buffer might be full...

Silverseas · October 18, 2019

Just now, Radium_Angel said:

Possibly. What kind of device are you copying the file to? An SSD, HD, flash stick? That device's buffer might be full...

Thanks for the reply. I meant to include this in my original post I'm editing it now. I'm transferring between two SSDs with read/write speeds of over 400MB/s, tested in CrystalDiskInfo.