Check the logs for a %ASA-6-302014 message at the time of the teardown. This will provide you with the reason that the connection closed. See the following link for a list of teardown reasons with their explanations:
Login to the FXOS chassis manager.
Direct your browser to https://hostname/, and log-in using the user-name and password.
Go to Help > About and check the current version:
Check the current version availa...
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...