The unit in question is archer C5 not Archer C50.  No C5 in the list and can't figure out how to add freeform model information.

I have successfully used two 160GB HDD as network storage for several years.  Both drives are formatted ntfs. Both have their own power supply.

I'm trying to upgrade network storage with 3TB backup plus.  The backup plus has it's own power supply.  The backup plus is formatted ntfs.

Backup plus works fine when connected directly to an individual PC but will not work when attached to the archer C5. 

When the backup plus is attached to USB, the C5's usb light blinks steady and the router's UI webpage will not come up in any browser. No error message, just working, working goes on forever.  All other router functions (internet etc) work fine during this time. 

Once the backup plus is disconnected the UI webpage is accessible again.  I have tried all possible ways (there are two usb 2 ports) to attach the backup plus to archer c5 usb with no success.  I have left the backup plus connected for several hours hoping the archer c5 would figure it out with no success.

I've reviewed reams of documentation and articles to see if it is a size limitation problem with no luck.  

Can anyone help?

Thanks for your time.  I apologize if my post is to the wrong forum.  Please correct my error.

All the best,

Peter