External hard drives to use with comcast/cisco dvr

Ok, I am really trying to find info regarding what hard drive are compatible with comcast dvr, specifically is my 500gb passport portable compatible in any way with my comcast cisco rng-200n dvr cable box. I am being pointed to the WD 1tb My Book dvr expander, but in comcast’s description it reads WD external hard drives up to 1tb. That leads me to think any WD hard drive could work as long as it has an esata port. So I bought a usb to esata adapter and plugged the drive into the dvr, but it does not power up. Then I formatted my passport from it’s default ntsc to exfat, and am just waiting for that to finish before I try it in the dvr, but something tells me I’ll get the same result. 

My question: Does anyone have any experience using any other external drive other than the 1tb my book? Does anyone know if it’s possible to use another western digital hard drive to expand the dvr system? Thank you. I really appreciate any input you have.

Hi there and welcome to the WD community.

I suggest contacting the cable company on this case since they would let you know if this is possible, they could let you know what the biggest size drives they support. You can try to get a Mybook AV unit. Here is a link to the WD store on which you will be able to see the unit: