The standard EDID on a 3G Just Add Power Transmitter does not currently display a 4K DirecTV at it's native resolution settings. To get an DirecTV to output 4K video, the default EDID must be modified.
The Default EDID in firmware B2.0.0 uses 4K60 as the Maximum Video Resolution. However, EDIDs are not updated during a firmware update - so as to not ruin any custom EDIDs that may be applied.
For a device on firmware B2.0.0 or later, the webUI will report "Default EDID" even if the default EDID for B2.x.x is not applied, because there is no way for the webUI to tell the difference between the B1.x.x default EDID and B2.x.x default EDID.
Please follow the instructions below even if your Transmitter webUI reports "Default EDID".