I upgraded my Asus O!Play media box to the latest release 1.30P on Sunday and CIFS support really improved.
Before that upgrade I had to open the Network folder twice to get my local Samba server into the list, now it will detect that immediately.
You can download the release at the Asus Support Download Site. Please choose Multimedia for the product, Digital Media Player for series and finally the model O!Play HDP-R1.
A popup will ask for the operating system, select Linux and you will find a list of downloadable files in return.
The item Firmware contains the archives with latest firmware releases. Please choose the file properly, and respect any comments about NTSC resp. PAL. In the moment the version number contains a suffix
Conduct the upgrade on your OWN RISK by extracting the archive on a USB stick. This will provide a HowTo with details of the installation.