Recovering Data from Synology NAs DS213J

On Thursday afternoon my NAS spat the dummy and my network shares stopped working, became painfully slow and the CPU is running at 100%

The two 3TB drives are showing as OK.

I put one of the drive into my computer and booted into ubuntu and it could not see the drives.

I then found some 1TB drives and put in the NAS and it is working perfectly.

I have then put the drive into a USB caddy and the NAS says it does not support that format.

I have put one of the 3TB drives back into the NAS and am able to copy stuff off the 3TB drive to a USB drive which is painfully slow.

At this rate it will takes weeks, the data itself is not hugely important but Nice to have, I would normally have a backup off all my data but I have been using that server for something else and Murphys law says something is going to go wrong now.

Any idea's on how to put the drive into a computer and recover the data at speed?

It appear that the synology OS has done a bad update as I was fine in the morning, works fine with a fresh install so all I can summise is an update gone bad.

Cheers

John