APNs socket hang up error.

Hi.

I use Google Translate because I can't English.

I'm sorry if I do not understand the sentences I wrote...

Push notification service is implemented by Node.js.

From 2018/02/09, socket hang up occasionally happens when connecting to APNs. It is still occasionally still.

The connection method to APNs is TLS connection to gateway.push.apple.com:2195 and push distribution is done

This is the log when the event occurred.

[2018-02-10 17:35:51.094] [ERROR] [10913] - MSG:498619[2] | Error occured send APNs: { [Error: socket hang up]
stack: 'Error: socket hang up\n    at TLSSocket.onHangUp (_tls_wrap.js:942:21)\n    at TLSSocket.g (events.js:199:16)\n    at TLSSocket.EventEmitter.emit (events.js:129:20)\n    at _stream_readable.js:898:16\n    at process._tickDomainCallback (node.js:372:11)',
code: 'ECONNRESET' }
Error: socket hang up
at TLSSocket.onHangUp (_tls_wrap.js:942:21)
at TLSSocket.g (events.js:199:16)
at TLSSocket.EventEmitter.emit (events.js:129:20)
at _stream_readable.js:898:16
at process._tickDomainCallback (node.js:372:11)
[2018-02-10 17:45:52.211] [ERROR] [10913] - MSG:498621[2] | Error occurd send APNs: { [Error: socket hang up]
stack: 'Error: socket hang up\n    at TLSSocket.onHangUp (_tls_wrap.js:942:21)\n    at TLSSocket.g (events.js:199:16)\n    at TLSSocket.EventEmitter.emit (events.js:129:20)\n    at _stream_readable.js:898:16\n    at process._tickDomainCallback (node.js:372:11)',
code: 'ECONNRESET' }
Error: socket hang up
at TLSSocket.onHangUp (_tls_wrap.js:942:21)
at TLSSocket.g (events.js:199:16)
at TLSSocket.EventEmitter.emit (events.js:129:20)
at _stream_readable.js:898:16
at process._tickDomainCallback (node.js:372:11)

I have not changed the web application recently.

• Please tell me what is the cause of this event occurs (socket hang up) and if there is a way to avoid something if this event occurs.
• Have you updated or changed APNs near February 9, 2018?