Very slow file copying over gigabit network between 2 macs running Mojave

Have you verified on the Mini that it is really connected at 1Gb?

System Preferences->Network->Advanced->Hardware

Reason I ask is that the math seems to indicate it is connecting

100 Mb. If a cable or connector is bad, it will revert to this if it

is not totally faulty. Gigabit ethernet uses all four pairs but

100 megabit only uses two. There could also be something

else wrong as well that is limiting to 100 Gb.

htmanning wrote:

I've tried to turn of packet signing per this link with no luck.

https://support.apple.com/en-us/HT205926

Disabling/enabling SMB packet signing really doesn't matter in this scenario. It tends to be better suited when the SMB server is a non-Apple entity, like a Windows server or a NAS. Apple has pretty much drank the SMB Kool-aid and has abandoned AFP for use only for Time Machine backups to a Time Capsule (TC). macOS Mojave has full SMB 3.x support.

If you get a chance to try Throughput Test and should nothing significant come up as the result, the next step would be to perform a data capture of a file transfer using something like Wireshark. Analyzing the results make indicate that there is a network bottleneck during the file transfer process. Unfortunately, it cannot tell you why. That would take a bit more detective work. There is a lot of info on using Wireshark for this exact purpose on the Internet.

You mention that everything is hardwired. Are both of these devices directly connected to the AirPort Extreme or are there any Ethernet switches between them?

Are both Macs connected by wireless to the AirPort Extreme base station? Have you run any wireless throughput tests between these two devices to see if the issue is more network than file transfer protocol related? That is, use something like iperf or a GUI equivalent, like TamoSoft's Throughput Test? This would establish a throughput baseline to work from.

If you run a simple ping between these devices, do you see any dropped packets or significant RTT times (> 10ms)?

Both the AirPort Extreme and Time Capsule will use SMB 1.0 for basic file transfers, but use AFP for Time Machine backups. The Apple base stations do not support SMB 2.x or 3.x. However, you can "force" which protocol to use for file transfers by how you mount their drives, i.e., afp:// or smb://

Again, without knowing your complete network configuration and how you have these devices interconnected it would be difficult to say why you are seeing "better" throughput performance with the AirPort Disk vs. Mac-to-Mac transfers.

htmanning wrote:

.....

I also use this server for Time Machine backups for one of my Macs. I reboot it automatically weekly, but maybe there was some caching issue. ...

FWIW, I never reboot my MacMini I use as a server except for

macOS updates and if I think there may be an issue (which is rare).

So far, its been online since just before Christmas which was last time

I did a system update. Of course it is on a UPS and runs 24/7.

I also have content caching enabled. Perhaps that was causing something, although the reboot and resetting of the NVRAM should have resolved it. ..

I also have Content Caching enabled and the last time I messed with that

was about 4-5 months ago when I updated the external drives to SSDs.

Hello,

Try running these following test:

How to reset the System Management Controller (SMC) on your Mac - Apple Support

Reset NVRAM or PRAM on your Mac - Apple Support

How to use Apple Hardware Test on your Mac - Apple Support

Something you didn't mention or may have tried already,

does the slow transfer also occur when transferring from

the Mini to other devices? From Mac to Mac (not the Mini)?

FWIW, this really isn't comparing Apples to Apples (no pun intended),

but I just did a test on my system. I have a 2010 MacMini that I

am using as a home server/iTunes Master library which only has

USB2, an AEBS (the last pizza box version), and my test machine

is a late 2013 27" iMac. I transferred one of my back up folders of images

that was 15 GB and around 1010 files and the transfer took about 8 minutes.

The 8 minutes was limited by USB 2 of the Mini and the number of files.

This also seems close to your experience with AEBS>Mac transfers given it's a

Photos library which will have a lot more small files involved.

All machines are configured for SMB transfers, the Mini is the most current

High Sierra and the iMac is the most current Catalina. All the drives used on

the machines are APFS (recently upgraded my external drives on the Mini to SSD).

Something does seem a bit amiss with your Mini that you are using as a server.

Here is another thought on your Mini, I hope you don't have any 3rd party

antivirus software on the Mini? Also, do you have any other apps or utilities

running on the Mini?