[Users] WAN access of oVirt

I've installed engine on 192.168.1.80 with hostname engine.example.com, node on 192.168.1.90 with hostname node.example.com. And I've started websocket-proxy service on engine.example.com, I can access VM via noVNC normally. Now suppose my WAN IP is 123.45.67.89 with DOMAINNAME engine.example.com, and I've mapped 443,6100 to 192.168.1.80 on the router. After I add this record "123.45.67.89 engine.example.com" to client hosts file and visit engine.example.com to access VM via noVNC, I get an error whose code is 1006. How to access VM from WAN in this senerio?