[rabbitmq-discuss] Heartbeat missing with heartbeat

[Alexey]

We are using the last .NET client and server version 2.8.1
After enable heartbeat we got a strange behaviour: consumer often
disconnected with the following message:
Reason: AMQP close-reason, initiated by Library, code=0, text="End of
stream", classId=0, methodId=0, cause=System.IO.EndOfStreamException:
Heartbeat missing with heartbeat == 5 seconds

Also after enable heartbeat we got the following message
Consumer 13b04f46cd014283903d9d93ee7a4029 is being shutdowned.
Reason: AMQP close-reason, initiated by Peer, code=406,
text="PRECONDITION_FAILED - unknown delivery tag 1", classId=60,
methodId=80, cause=

We are using rabbitmq cluster and some tasks is never removed from
queue, but processed with consumers again and again.

Would appreciate for any help
Alexey