ESP8266 response error -301 | ESP Wi-Fi | Forum

Hello,
I am using ESP8266 Wroom-02 and the latest version library: ThingSpeak ver.1.4.3 for Arduino. I'm using a simple example from the library.
When I use the function: delay (20000) everything works fine. But when instead of the delay function it uses the sleep function: ESP.deepSleep (20,000,000) the thingspeak server returns error -301 (Failed to connect to ThingSpeak)
I receive update successful connection ( code 200) a reliable connection once every several dozen attempts.

A part of my sketch:

...
void loop() {

...

// Write to ThingSpeak. There are up to 8 fields in a channel, allowing you to store up to 8 different
// pieces of information in a channel. Here, we write to field 1.

int x = ThingSpeak.writeField(myChannelNumber, 1, number, myWriteAPIKey);

// Check the return code
if(x == 200){
Serial.println("Channel update successful.");
}
else{
Serial.println("Problem updating channel. HTTP error code " + String(x));
}

delay(20000); // Wait 20 seconds before sending a new value *******************- this works well

// ESP.deepSleep(20000000); //*************************************************- this does'n work!

}

Anyone have an idea to solve the problem?

BR
Greg