Error: Hyper-V could not replicate changes for virtual machine 'XXX': The connection with the server was terminated abnormally (0x00002EFE).

Hi,
I have 4 Hyper-V servers that replicate different VM's to each other.
2 of them in subnet A and 2 in subnet B. Subnets are on the same physical LAN.
Between the subnets there is a firewall (in addition to the Windows Firewalls). I should mention that the firewall is a UTM (Kerio Control).
When replicating to and from the 2 in subnet A replication occurs successfully.
When replicating to and from the 2 in subnet B replication occurs successfully.
However, when replicating across the subnet from and to any server I get the following error:
Hyper-V could not replicate changes for virtual machine 'XXX': The connection with the server was terminated abnormally (0x00002EFE).

-I can ping between the servers
-I have checked that the names can be resolved via DNS
-I have opened up the following ports on all firewalls: 135,80,443,6600,445,3343,49152-65535
-I have tested if ports are open via telnet

Any ideas?