cifs mount differences: mount command vs fstab entry

I am experiencing a difference between two methods of mounting a volume. If I use mount at the command line:

sudo mount -t cifs -o sec=ntlmssp,vers=1.0,credentials=/home/bob/.credentials,uid=1001,gid=1001 //192.168.20.16/bob /home/bob/home

then all is good. If however I use a (what I believe to be identical) fstab entry:

//192.186.20.16/bob /home/bob/home cifs sec=ntlmssp,vers=1.0,credentials=/home/bob/.credentials 0 0

Then I get the following failure:

mount error(2): No such file or directoryRefer to the mount.cifs(8) manual page (e.g. man mount.cifs) and kernel log messages (dmesg)

dmesg helpfully tells me:

[ 1406.873877] CIFS VFS: Error connecting to socket. Aborting operation.[ 1406.873906] CIFS VFS: cifs_mount failed w/return code = -2

I don't believe I have the path wrong - as the command line forsion to the exact same path works - so I think the no such file or directory is a misnomer. The error code is saying something similar but I can't believe that either.

Any help would be greatly appriciated as my current workaround of a startup script to run the command line version makes me sad! (This is after a fresh install of Ubuntu 20.04.1 LTS, moving over my previous working setup.)