IN looking at CONN_SUP_TIMEOUT below:
#define CONN_SUP_TIMEOUT MSEC_TO_UNITS(4000, UNIT_10_MS) /**< Connection supervisory timeout (4 seconds). */
It says the units are 10 ms. if you take 4000 * 10 ms, you end up with 40000 ms which = 40 seconds - not 4 seconds.
Also for MIN_CONN_INTERVAL as below:
#define MIN_CONN_INTERVAL MSEC_TO_UNITS(100, UNIT_1_25_MS) /**< Minimum acceptable connection interval (0.1 seconds). */
It says units are 1.25 ms.If you take 100 * 1.25 ms, you get 125 ms which = 0.125 seconds not 0.1 seconds.
Am I missing something here?