+---+
      | c |\
      +---+ \              +---+
             \-----UDP-----| D |------TCP------+---+
      +---+                | O |               |   |
      | c |--------TCP-----| T |------TCP------| S |
      +---+                | S |               |   |
             /-----UDP-----| G |------TCP------+---+
      +---+ /              +---+
      | c |/
      +---+
      example.com       example.net           example.net
      DOTS clients      DOTS gateway (DOTSG)  DOTS server