Been having this issue when transferring files (Most often large files or multiple large files). Will get the following error code. Seems to happen on all of my computers connected to the ISIS, but won't occur when transferring the same data on other NAS drives. Any idea? The machines I'm transferring these from are all Mac running either 10.15 or 10.16.

I don't know if this is helpful, but I've seen this issue on Big Sur clients when interacting with Samba shares and trying to copy larger files. Finder throws the error code then unmounts the server.

I think the ISIS is using its own properitary sharing and file system so this might not be related at all. When I've had this error code on macOS before I ran a packet capture on the server side and saw multiple TCP retransmissions followed by the macOS client resetting the port connection to the server which lead me to believe it was a macOS issue.

Things I've done in the past:

1. disable Spotlight indexing on mounted Volumes. in terminal:

mdutil -i off /Volumes/workspace

2. disable SMB multichannel

Create the file:

/etc/nsmb.conf

Add the line:

mc_on=no

3. disable TCP delayed acknowledgement.

Create the file:

/etc/sysctl.conf

Add the line:

net.inet.tcp.delayed_ack=0

Save and reboot

I would also recommend trying the latest NEXIS client for interacting with the ISIS storage workspaces (if your ISIS is on the latest version).