12 DB attenuator for Xfinity Enhanced Speed areas

My service area was recently upgraded to the enhanced speed tiers. Where can I acquire a 12 DB PAD (attenuator)? My concern is the UPLOAD & OFDMA.

Channel 1-32 Download channels: -1 to 1 DB.

OFDM is 1 DB for 611 MHZ

OFDM is 3 DB for 803 MHZ

UPLOAD 49-50 DB for 4 channels

OFDMA 57 DB 

Xfinity my modem has not been rebooting so that's good.