Molex ONT

In some sticks, such as those based on Lantiq chipsets, the serial interface is exposed in the upper pins of the ONT, in order to read them there are two possibilities:

the use of an SFP molex (farnell) to which four wires are to be soldered and the other pins removed. This makes the adapter compatible with a single serial combination.
the use of a board to which the SFP molex is soldered, exposing the main SFP pins.

Example of how the SFP-TTL adapter is to be connected

Example of how the SFP-TTL adapter is to be used with a custom board

If you want to make your own board, here are some ideas:

the components to be soldered are instead:

1x MOLEX SFP (like Molex-744410001 lcsc, farnell)
2x pinout 2x10 (like MINTRON MTP125-1210S1)

Example of the final board with these components on the EasyEDA platform.