Fiber Mountain Inc.

Any device whose MAC address begins with D4:55:56 has a network interface built by Fiber Mountain Inc.. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address.

OUI prefix

D4:55:56

Organization

Fiber Mountain Inc.

Address

700 W Johnson Ave Cheshire CT US 06410

Source

IEEE OUI registry

Have a full MAC address? Look it up— we'll also tell you if it's a randomized (private) address rather than a real manufacturer prefix.