hi there,
And this problem too, the internet, server computer can normally use internet but clients can not, why?
remove this from your server config
push "redirect-gateway def1"
And it seems to me that it can't be used programs like LanTalk NET which are for communication in LAN networks.
This program automatically register other user if he has installed same program.
Can they be used over ovpn network?
if this software uses broadcasts it wont work in routing mode (tun)
you need to setup openvpn in bridging mode.