Need advice about resetting to Factory Default on rn104

So, after the 40th forced resync since upgrading to 6.4 on my rn104 (system hangs/freezes and I have to unplug&plug the power), I decided to do a reset to factory default.

My setup is the following, with two 3TB disks and two 2TB disks:

Also, the actual usage is the following, with 3.36TB free of a total of 6.35TB:

Since I don't have other external storage available at the moment, I was thinking of:

1) removing one 3TB disk and letting ReadyNas do its resync with the remaining disks (one 3TB and two 3TB)

2) reformatting the removed 3TB disk and use it as a backup disk for the data stored in the ReadyNas

3) resetting ReadyNas to factory default

4) restoring to ReadyNas the data from the 3TB backup disk

5) re-installing the 3TB disk into ReadyNas

6) letting ReadyNas do the new resync

Is this above a correct procedure? Any mistakes or better solutions?

Thank you in advance!

p.s. Logs show no problem whatsoever with the disks, but unless I use ReadyNas in read-only mode, all of a sudden it freezes and doesn't let me other choice but unplugging the power and restart.

And everytime I do so, it has to resync, and it takes about 36hours to finish.

I tried every solution on the forum, from removing snapshots to disabling apps, but nothing: it keeps freezing. Also, even if I try to "access" from different positions (l don't know the exact term), like moving some files via SMB and others via http (e.g. with the browser interface) at the same time, the system hangs after a few minutes...