Hi Klaus, there is known issue with the first retransmission interval. As openser use unique timer with cadence of 1 second. So if the retransmission is set (added into timer) at second n+500 ms, that the timer will hit at n+1 seconds, resulting in a 500 ms period instead of 1 sec. It's about time quantification of the timer and the time linearity of the insertion in the timer. Hope I manage to put it in words in an understandable way ;) regards, Bogdan Klaus Darilion wrote: