Server crash when sending an ios notification

When I try to send a notification to an ios device my server crashes with the following message:

Error: 139874953426816:error:14094416:SSL routines:SSL3_READ_BYTES:sslv3 alert certificate unknown:../deps/openssl/openssl/ssl/s3_pkt.c:1300:SSL alert number 46

    at SlabBuffer.use (tls.js:235:18)
    at CleartextStream.read [as _read] (tls.js:455:29)
    at CleartextStream.Readable.read (_stream_readable.js:341:10)
    at EncryptedStream.write [as _write] (tls.js:369:25)
    at doWrite (_stream_writable.js:226:10)
    at writeOrBuffer (_stream_writable.js:216:5)
    at EncryptedStream.Writable.write (_stream_writable.js:183:11)
    at write (_stream_readable.js:602:24)
    at flow (_stream_readable.js:611:7)
    at Socket.pipeOnReadable (_stream_readable.js:643:5)
    at Socket.emit (events.js:92:17)
    at emitReadable_ (_stream_readable.js:427:10)

I’ve put the entrust_2048_ca.cer in /opt/AppName/app/programs/server/assets/app/

Running

openssl s_client -connect gateway.push.apple.com:2195 -CAfile entrust_2048_ca.cer -cert PushChatCert.pem -key PushChatKey.pem

returns

Verify return code: 0 (ok)