NtpClient | NtpClient based on gmag11 's library

Calculating elapsed time right after the user input will fix your issue.

This issue is because it's sorted as a string.

If your data is 1, 2, 3, 10, it will be ordered 1, 10, 2, 3 because the string 10, comes before the string of 2

So change how the data is stored; either as a Timestamp, convert to double or it must be a string use yyyymmddhhmmss

So this "2021-2-9 10:0:0" would be

IMHO, the approach is straight forward:

1. Get the NTP time (I'll call it now)
2. Define the time you want to run the code (runat)
3. Calculate the difference
4. Sleep for that time
5. Do whatever you want at that time

Note that asking NTP servers for the time will itself take some time. So if you print the NTP time as part of the step 5, it will always appear late. I'll use the local time to compensate for that in the code below.

You define udp in RealTimeService::_createNtpClient() and pass it to NTPClient. NTPClient will continue to need it after RealTimeService::_createNtpClient() returns, but udp will become invalid. Even if NTPClient copies it, its destructor is called, invalidating the resources it used.

You need to change udp to be an instance variable so that it will survive as long as _ntp does.

host.configManager.firewallSystem.EnableRuleset(id='ntpClient')

You could try to assign tasks explicitly to a core.
When you start playing with ESP32 multi core code execution be aware of the following issues:

• Both the setup and the main loop functions execute with a priority of 1.
• Arduino main loop runs on core 1.
• The execution is pinned, so it’s not expected that the core will change during execution of the program
• On FreeRTOS (the underlying OS), tasks have an assigned priority which the scheduler uses to decide which task will run.
• High priority tasks ready to run will have preference over lower priority tasks, which means that as long as a higher priority task can run, a lower priority task will not have the CPU.
• CAUTION shared resources like Serial might be potential issues. Due to two core tasks accessing uncoordinated the same hardware may lead to deadlocks and crashes

For implementation purposes, you need to take in consideration that FreeRTOS priorities are assigned from 0 to N, where lower numbers correspond to lower priorities. So, the lowest priority is 0.
First of all, declare a global variable that will contain the number of the core where the FreeRTOS task to launch will be pinned

I think it may be because your input is incorrect, an example piece: