@MichaIng: ty! 
OK, i resolve by creating an other directory, copy the private key, and chown only for _turnserver user…
with another group as “ssl”, and chmod 0440, that’s not run. 
it’s weird because there is no need to change the server certificate!
another question: how i can block SSL23 usage… i want only TLS1.2!
i uncommented:
no-tlsv1
no-tlsv1_1
But, i’ve on start message:
Dec 19 17:30:21 srvr turnserver: 0: SSL23: Certificate file found: /etc/ssl/acme/mydomain.net.cert.pem
Dec 19 17:30:21 srvr turnserver: 0: SSL23: Private key file found: /etc/ssl/acme/turnserver/mydomain.net.privkey.pem
Dec 19 17:30:21 srvr turnserver: 0: TLS1.2: Certificate file found: /etc/ssl/acme/mydomain.net.cert.pem
Dec 19 17:30:21 srvr turnserver: 0: TLS1.2: Private key file found: /etc/ssl/acme/turnserver/mydomain.net.privkey.pem
Dec 19 17:30:21 srvr turnserver: 0: TLS cipher suite: ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AES:RSA+3DES:!ADH:!AECDH:!MD5
Dec 19 17:30:21 srvr turnserver: 0: DTLS: Certificate file found: /etc/ssl/acme/mydomain.net.cert.pem
Dec 19 17:30:21 srvr turnserver: 0: DTLS: Private key file found: /etc/ssl/acme/turnserver/mydomain.net.privkey.pem
Dec 19 17:30:21 srvr turnserver: 0: DTLS cipher suite: ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AES:RSA+3DES:!ADH:!AECDH:!MD5