Strange behaviour since several version 11.x

hi all,
i have some really strange problem wich let the users complain.
first if you have an android phone the reaction time is up to 30sec to start ring … well thats a android problem so far BUT: Ast retry the same message 5 times but not sending anything out on the ethernet
, but after some time i seen the 5 retry at once going out on ethernet.

then next problem:
a sip client is only able to connect once… no problem last connect counts
but how the hell can it been seeing that
[2014-08-04 13:28:51] NOTICE[7294]: chan_sip.c:29623 sip_poke_noanswer: Peer ‘3011c’ is now UNREACHABLE! Last qualify: 5013
[2014-08-04 13:29:22] NOTICE[7294]: chan_sip.c:29623 sip_poke_noanswer: Peer ‘3011c’ is now UNREACHABLE! Last qualify: 4717
with pingtimes of 300msec between them without any packetloss

sometimes connection just get hangup initiated to both sides from the server … no reason discovered not on the console not on the log

all those problems are appearing on basic configuration with just changed the existing client to match the credencials.
nearly same behaviour

does anyone seen similiar effects ?