Why does the IP phone not receive an address from the VPN server, although there is a connection?

Question

VPN

There is a dlink 150se phone with the latest firmware and l2tp support
There is a Softether VPN server (hereinafter referred to as SE) on vps, which is a "virtual hub" and a gateway for a number of machines clinging to it (corporate mini-grid).
When I fill in the data for connecting the phone to SoftEther Vpn, it connects, it is in the SE logs and active sessions, the user who is connected is visible. But the phone does not receive the address. In SE, respectively, the address is also not displayed. That is, the fact of the connection is there, but the device does not have an address. Just 0.0.0.0 .
For example, I connected the same phone to the l2tp server on Kerio Control and everything worked right away. The address is received in a second and everything rings perfectly and works.
Please help. The head has already been broken. In my case, I need the circuit exactly SE + Dlink150s
ps. - tried another phone.
- openvpn is not in this length.