Disc change

Hello,

I need advice, I have at home 2 x My Cloud Home 8TB (3 generations) as a corporate NAS and Asustor AS6102t with 2 x 1TB as a home media server. I would need to replace the disks so that 2 x 1TB is in My Cloud Home and 2 x 8TB in Asustor. I’ve tried some forum tutorials (uploading firmware and converting to GPT in Ubuntu), but so far I haven’t been able to run My Cloud with any other drive.

I will be very happy for advice