Connecting vpn users to local LAN USGPRO4

I have connected a usg pro 4, works nice and fast. it has and the VPN users (RADIUS) are on
I can navigate to the management interface from the vpn connection but if I connect and iphone and try to use zoiper, it will not connect to the brandstream. It will connect to the grandstream while in the LAN but not if I am outside on a vpn.

my linux boxes can connect in and do just about everything browsing, managing the key, the usg pro, access the grandstream management interface as well as the phones, etc. phone can do the same when the vpn is connected but it will not connect zoiper to the grandstream.

Any suggestions?