Solder usb_rref (also known as USB_REXT) 6,19kOhm resistor
(A note by another user about what follows: this 6.19 kOhm resistor is already on the board, it is R66 at the corner of U1 on the top side (we can see it on the picture showing the serial header further below). Soldering a resistor on footprint R13 as shown here would be actually a pull-down on EJTAG_SEL, disabling enhanced JTAG, which is already enabled thanks to R11, a zero-ohm resistor connected to 3.3 V supply. In order words, soldering the resistor as described here is like soldering a resistor between the 3.3 V rail and ground. See schematic dir615c1.pdf) (I soldered 4.7K, but later I got a dir-615c1 circuit with usb_rref=6.19K 1%) at the bottom of the pcb near ar9130 processor (look photo). I soldered 0805 size because didn't find 4k7 0603 size at home. If your solder skills not good - ask to solder this in any cellphone repair service (size of 0603 resistor - 1.6×0.8 mm)