AlwaysON cluster issues

Hi, we've been having some serious issues with our AlwaysON cluster configuration.

This is the short description of the scenario:
- Windows Server 2008R2 (Active Directory and DNS) (Subnet 1)
- Windows Server 2012R2 (SQLServer 2012 Cluster Node 1) (Subnet 2)
- Windows Server 2012R2 (SQLServer 2012 Cluster Node 2) (Subnet 3)

First of all, the cluster hadn't enrolled in the DNS server from it's creation.
Right after cluster creation we've been having' a "DNS server failure" error showing up
in cluster's log every 10-15 minutes.

After manually create the DNS record and giving the apropiate permissions to the CNO and
node accounts, the error changes to 'Handle is invalid' and is still showing up every
10-15 minutes.

Anyway, it seems that the AlwaysON feature is working somehow, and the application can access
the database through the Availability Group listener. But, recently, the SQL Server Log has 
started to show the following message :"The Service Broker endpoint is in disabled or stopped state."
and since then, we are having intermitent access to the database with no apparent pattern
of ocurrence.

Any advice?