WD Smartware not finding Passport attached to Asus N66U router

I’ve attached my passport to my new ASUS RT-N66u router and WD smartware doesn’t see it.  How do I fix this?  The router page shows it sees the Passport attached.

Thanks

Smartware does not support backing up to My Passport when connected to a router.

In order for Smartware to see the drive it needs to be attached to the computer.