It's entirely possible that getServerTime() could fail in which case I'd want to keep calling it until it succeeds or some timeout is reached.

But there is no way for me to know if it was successful since it's private and I only get access to it indirectly through getUnixTime() which is skewed by millis().

So ultimately, I have no way of knowing if I can rely on what getUnixTime() is telling me other than to use some "less than some smallish-value" type heuristics.

I think the library either needs a flag to indicate that the time is accurate (i.e. there was a successful NTP transaction) or getUnixTime() should return 0 until the time is accurate the way getServerTime() does.

Hello! Please help!
Im using SIM800 GSM via TinyGSMclient library, but no examples of code how use EasyNTPClient in my case. Im search a lot but not found how tu use udp: Reference to an UDP object with TinyGSMclient.h.
Is exist many examples of ethernet or wi-fi but none of GSM.

I suggest adding a line to setTimeOffset() so that it changes mServerTime by the offset once the function is called.

Steps:

1. getUnixTime()
2. setTimeOffset(offset)
3. getUnixTime()

Expected Behavior:

• Return unix time + offset

Actual Behavior:

• Return unix time

Changing:
void EasyNTPClient::setTimeOffset (int offset) { this->mOffset = offset; }
to:
void EasyNTPClient::setTimeOffset (int offset) { this->mOffset = offset; this->mServerTime = this->mServerTime + this->mOffset; }

On some boards (e.g. ATmega like Uno) "int" is only 2 bytes and thus is capped unsigned at only roughly 65000. As mUpdateInterval holds milliseconds this more or less means that you can have 1 minute max as update interval.
I suggest to set the type of mUpdateInterval to uint32_t, which is always right.

I'm gone mad using static IP: time is not retrieved. After a while I've discovered that if you want to use static IP, you must explicit also DNS in the wifi config:

#define USE_STATIC_IP
// data used for static IP configuration:
#ifdef USE_STATIC_IP
  IPAddress ip(192,168,1,38);		// ip address you want to assign to your board
  IPAddress gateway(192,168,1,1);	// router address
  IPAddress subnet(255,255,255,0);	// subnet mask
  IPAddress dns1(8,8,8,8); // dns 1
  IPAddress dns2(8,8,4,4);  // dns 2
#endif

// [...]

#ifdef USE_STATIC_IP
    WiFi.config(ip,gateway,subnet,dns1,dns2);
  #endif
  WiFi.begin(ssid, password);

I think It's better include this snippet in the example for ESP8266.
Thank you for the library: it's the simplest one