Well, I have successfully started a render of a still image over network. I just followed Dale's advice on changing the ports. BUT, I went even further by configuring each computer on a VPN (although all computers are already on a physical LAN, hehe). When all computers are connected to a VPN, Hypervue seems to run flawlessly and smoothly.

Weird...

I will try to resume rendering an animation over network after my still image has completed. Thank you all for the helpful advice.

I will be back...