苹果推送通知突然开始抛出一个错误:套接字被远程关闭

我使用以下代码通过apple推送通知api发送通知。它工作得很好,直到几天前它开始抛出一个错误:

插座被远程关闭

这是我正在使用的代码:

p8key = "*****"
private_key = OpenSSL::PKey::EC.new p8key

token = JWT.encode(
  {
    'iss': "*****",
    'iat': DateTime.now().to_time.to_i
  },
  private_key,
  '***',
  header_fields=
  {
    'alg':"***",
    "kid": "***"
  }
)

client = NetHttp2::Client.new("https://api.push.apple.com:443")
client.on(:error) { |exception| puts "Exception has been raised: #{exception}" }

msg = "Hello"
body = { aps: { alert: msg, sound: "sound.mp3", badge: 1 } }.to_json

request = client.call(
    :post,
    "/3/device/#{recipient.push_token}",
    body: body,
    headers:
    {
      'authorization' => "bearer #{token}",
      "apns-topic" => "com.dogtime.dogtimeinit"
    }
  )

每次我尝试发送通知时,它总是抛出错误,知道它可能来自哪里吗?