Rsync backup problem using dyndns hostname

I have two readyNAS drives, one at work and one at home, they have both been working fine but I wanted to put a larger drive in the one at home so I started again with setting up my backups.

When I started again the firmware in my home drive was updated v5.3.12

Since then my backups do not work when remote (i did backups when they were local to each other just fine) I have a DynDns account as the home drive "pulls" rsync backups from the work drive.

When I use the work IP address 86.140.XXX.XXX it works fine but when i use my "myworkname.dyndns.biz" it does not work.

Now in the short term I can just keep manually changing the IP address as it changes (not ideal) I cannot figure out why it no longer let's me use the hostname from dyndns, I have logged into dyndns and verified the IP hostname is forwarding the correct IP.

I can access my work router from home using the hostname so I know it works.

I get the error message 7077010011

Nothing else has changed that I am aware of, the work router has the same port forwarding rules for port 873, all I can think is that the new firmware has ruined it.

Any help would be appreciated.

Thanks