Failure with clean installation - receive 603 declined from PBX

first of all, you were not that clear in your previous suggestions.
this is the first time that you give me exact command to turn on debugs that are required.

I will try these and try to see what’s wrong in SDP, codecs etc.

about “incorrect network conf. /NAT” :
I’m sure this is not the case. I told you the reasons. there is no nat.
but still I don’t know what is a "good network configuration"
is there a clear example of this ?

about “router on remote end mangling packets” :
I have a working Asterisk+FreePBX configuration , using the same remote end. The new setup is just newer Asterisk on new OS.
So the problem can not be about remote end.