Issue with Target Disk Mode from Imac Mid 2011 to Imac Retina 2019

Hello All,

I hope this finds everyone well! I purchased a new Imac and need to transfer files from the older machine. I figured target disk mode would be the way to do so and I got the Thunderbolt to newer thunderbolt and the cables at the apple store.

The new machine is running Big Sur, 11.2.3 The file system is APFS.

The old machine is running High Sierra 10.13.6 and the file system is OS Extended Journaled.

I boot the machine into Target disk mode and the thunderbolt cable is connected, however, the volume never mounts. I can see the firewire and thunderbolt icon on the old machine move across the screen.

I dont see it in disk utitlity to be able to do anything with it either.

I am able to setup a connetion to the machine via my network using smb, however, its very slow and with the amount of data I have to get out of that machine (I've been using it for 10 years . WOW) I would prefer to do so efficiently.

Am I missing anything here?

Thank you in advance for any help provided!

Regards,

Alex