Proxmox 2 Nodes in Switch from WAN (10MBI) to LAN (1GBIT)

Hello Proxmox Freaks,

i have running to proxmox Nodes, when i do a qcow offline migration with rsync I only get 10MB / S .
The Nodes only know each others from their "WAN-IPs" ...
in the last days connected the two nodes directly with a GBIT Switch.
Both machines are able to ping, to connect ssh trew their LAN-Ips (gbit Ports)...

but the (live) Migration work only threw the Wan Ips ....

Is there any possiblity to change this to get them talking directly threw their lan interfaces ?
Wich config Files should i change to get live migration working ?
Could i ran into any problems ? Do i Have to rebuild the complete "Cluster" ?

Thanks a lot

tempes