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