Many thanks for trying to help both. I have tried what you suggested and this is the situation.
If I click the "browse" button in the last navigator software, it opens to show the same two folders that appear on both my desktop PCs. I can access any file on the drive doing it this way which is great news. If I try and back up the laptop to the NAS that works as well.
I did enable SMB2 on the link station as suggested devil but I’m afraid it still doesn’t show up in file manager.
So the good news is I effectively have full access to the drive. I can back up, view and move all the files on it. The niggle is that it still is invisible in file manager which I just don’t understand!
Thanks again for trying to help.