Using NAS for Time Machine back ups
I used to have an Airport Time Capsule, which died a while ago. So I bought a G-Drive and connected it to my Linksys router (MX4200). It seemed to back up my iMac (M1) and Macbook (Intel) fine. However, recently, when I tried to restore some files Time Machine would only allow me to go back a few days and it refused to let me open the sparsebundle via the Network. Apple Support thought the external drive corrupted and advised to reformat it and do a new backup again. I am currently doing this and so far it seems fine. However, I wonder if there are any issues in my setup that could have caused the earlier problem?
I'm also a bit confused on the various file formats used. To get the Linksys to see my external storage I had to format it as Mac OS Extended (Journaled), although I understand that this is the format required for Time Machine to work anyway? However, I've also read that having a system running APFS means you can't then do a time machine restore from a different file format - ie. Mac OS Extended. Then again, in Disk Utility, it shows the backup, in the container volume, as being an APFS volume. Is this macOS's way around it?
iMac Line (2012 and Later)