terminated by the cause "A client which is non-SoftEther VPN software has connected to the port." (code 5).

[master600]

I have a Softether VPN server which I can connect to this server with OpenVPN and Open SSTP applications with android.
I tried to develope an application so that I can connect with my own software. The connection is not stable and server rejects after few seconds. I provide the log here:

2024-03-30 14:07:50.396 SSTP PPP Session [x.x.x.x:4845]: The PPP session is disconnected because the upper-layer protocol "SSTP" has been disconnected.
2024-03-30 14:07:50.396 SSTP PPP Session [x.x.x.x:4845]: The PPP session is disconnected.
2024-03-30 14:07:50.726 Connection "CID-522" terminated by the cause "Connection has been disconnected." (code 3).
2024-03-30 14:07:50.726 Connection "CID-522" has been terminated.
2024-03-30 14:07:50.726 The connection with the client (IP address x.x.x.x, Port number 4845) has been disconnected.
2024-03-30 14:07:50.949 [HUB "DEFAULT"] Session "SID-TEST-[SSTP]-111": The session has been terminated. The statistical information is as follows: Total outgoing data size: 1183423 bytes, Total incoming data size: 48748 bytes.
2024-03-30 14:07:50.980 Connection "CID-523" terminated by the cause "The VPN session has been deleted. It is possible that either the administrator disconnected the session or the connection from the client to the VPN Server has been disconnected." (code 11).
2024-03-30 14:07:50.980 Connection "CID-523" has been terminated.
2024-03-30 14:07:50.980 The connection with the client (IP address x.x.x.x, Port number 4845) has been disconnected.
2024-03-30 14:08:10.020 On the TCP Listener (Port 443), a Client (IP address x.x.x.x, Host name "62.19.172.47", Port number 4706) has connected.
2024-03-30 14:08:10.020 For the client (IP address: x.x.x.x, host name: "x.x.x.x", port number: 4706), connection "CID-524" has been created.
2024-03-30 14:08:10.233 SSL communication for connection "CID-524" has been started. The encryption algorithm name is "TLS_AES_256_GCM_SHA384".
2024-03-30 14:08:26.137 Connection "CID-524" terminated by the cause "A client which is non-SoftEther VPN software has connected to the port." (code 5).
2024-03-30 14:08:26.137 Connection "CID-524" has been terminated.

I used okhttp library.
can any one have an advice for this issue please?
I would appreciate it.

Thanks

[solo]

Fix your SSTP implementation and integration, check again the source code of https://github.com/kittoku/Open-SSTP-Client