I was able to add the symlink using the info in this thread, but the docker container was not able to find the device when using the Add a Device parameter.
I was able to work around it by adding the device in Extra Parameters in the Advanced View though.
--device=$(readlink -f /dev/symlinkname)
In /etc/samba/smb.conf the SMB Extras config file is included before the Shares config file. This causes issues when trying to specify additional smb options for these shares.
# hook for user-defined samba config
include = /boot/config/smb-extra.conf
# auto-configured shares
include = /etc/samba/smb-shares.conf
should be changed to
# auto-configured shares
include = /etc/samba/smb-shares.conf
# hook for user-defined samba config
include = /boot/config/smb-extra.conf
Some forum topics I found discussing this issue