I set up a VPN tunnel between 2 Netgear FVS318v3 routers and it works for the first 5 5610 phones without a problem. For some reason when I try to bring up the last 2 5610 phones they just display discovering. I can unplug any 2 of the 5 that work and the non working ones will register. So it seems that I am limited to 5 phones over the VPN tunnel. Any ideas?