NFS and bad response times – did you set actimeo=0 ?

You should rather not and leave the set-up with its defaults.

actimeo=0 disables file and directory attribute caching. Only use it like this, if there are very good reasons for it.

Rick Sladkey's NFS utility "showmount"

• linuxreviews.org/man/showmount
• Rick Sladkey and Linux NFS [oreilly.com/openbook/linag2/book/ch14.html = Linux Network Administrator's Guide, 2nd Edition]

showmount is quite useful, if you want to examine the properties of NFS shares instead of just mounting it. I used it, when I found it troublesome to mount a share from a (Linux) virtual machine behind a NAT router (actually a VirtualBox VM host).

NFS mount behind NAT (virtualbox)

NFS mount behind NAT (virtualbox) | The GNULinux Community Portal

The situation and trouble described there is rather similar to my set-up (VirtualBox + NAT + Linux guest), just that my NFS server is a Synology DiskStation.

I added "insecure" to the options of this share, switched off "Enable NFS" on the DiskStation, made sure the option is still there, enabled NFS on the DiskStation again, finally mounted the share again, and it was there – what a surprise!!!

I still have a UID mapping problem with this set-up.

disk back-ups sorted, new scanning computer sorted – happily looking forward

Integrated my "new" Synology NAS into my back-up concept in practice; I can of course back up at home on the LAN, but I can also back up over WAN (which is the more crucial variant) – rsync-wise "of course", i.e. sort of "differentially". And for the time being rsync-ing to my NAS seems to work as well again. I can talk to the NAS Mac-wise ("AFS"), and through SSH / RSYNC / SMB, but I have not accessed it successfully through NFS yet – which would be nice for accessing it from (openSUSE) Linux.

I also manage again backing up to USB disks from my VirtualBox openSUSE guest OS.
But occasionally I install openSUSE updates, and they enforce OS restarts, which I usually delay for far too long, so in the meantime no back ups and no access at all to my "Encrypted Big Disk" outside my computer, where I keep all sorts of long-term data.

I got me a Mac Mini, that stays of course in the office room, and it talks to the printers and the scanner, and of course it talks to the NAS. So I can take, whatever comes in from wherever (I am referring to the letters in my mailbox, that I am supposed to take out on Fridays on my arrivals at home), and take that stuff to my "scanning facility" and get them scanned, move the files to the NAS, so I can pick them up from there from wherever. Even from outside over the WAN. If there's enough time, I can even name the files properly.

All this doesn't really do the work to be done itself, but it facilitates achieving things. It makes me look forward a little happier and more optimistic. I do know now, how to achieve certain things within my rather limited time.