SSL_do_handshake() failed (SSL: error:140760FC:SSL routines:SSL23_GET_CLIENT_HELLO:unknown protocol)

2019/04/18 09:17:08 [debug] 7527#0: accept() not ready (11: Resource temporarily unavailable)
2019/04/18 09:17:08 [debug] 7530#0: *4527 generic phase: 0
2019/04/18 09:17:08 [debug] 7530#0: *4527 generic phase: 1
2019/04/18 09:17:08 [debug] 7530#0: *4527 generic phase: 2
2019/04/18 09:17:08 [debug] 7530#0: *4527 tcp_nodelay
2019/04/18 09:17:08 [debug] 7530#0: *4527 SSL_do_handshake: -1
2019/04/18 09:17:08 [debug] 7530#0: *4527 SSL_get_error: 2
2019/04/18 09:17:08 [debug] 7530#0: *4527 epoll add event: fd:3 op:1 ev:80002001
2019/04/18 09:17:08 [debug] 7530#0: *4527 event timer add: 3: 60000:10435359446
2019/04/18 09:17:08 [debug] 7530#0: *4527 SSL handshake handler: 0
2019/04/18 09:17:08 [debug] 7530#0: *4527 SSL_do_handshake: -1
2019/04/18 09:17:08 [debug] 7530#0: *4527 SSL_get_error: 1
2019/04/18 09:17:08 [info] 7530#0: *4527 SSL_do_handshake() failed (SSL: error:140760FC:SSL routines:SSL23_GET_CLIENT_HELLO:unknown protocol) while SSL handshaking, client: 192.168.18.1, server: 0.0.0.0:10101
2019/04/18 09:17:08 [debug] 7530#0: *4527 finalize stream session: 500

Hi @liuzuxi
There is not enough information to understand TLS failure.
Could you please enable TLS debug log?

Could you please elaborate on your flow? What is the server? Have you set the CA trusted certificates?

Regards,
Mbed TLS Team member
Ron