I can't see my ESP8266 worker at pool.vkbit.com or public-pool.io

Good afternoon.

I'm a technologies teacher and I want to introduce my students in Bitcoin mining.

In LeafMiner you suggest pool.vkbit.com, but when configured, I can't see my ESP8266 worker at it!
I tried also with public-pool.io, but I have the same problem.
I only can view my device at pool.nerdminers.org, but I prefer the last one.

Do you know where can be the problem? What can I do?

Thanks a lot.

No repository file, test, or entry point is identified. Start by tracing the ESP8266 pool configuration and worker-reporting path for pool.vkbit.com and public-pool.io, then compare it with pool.nerdminers.org; done means identifying the cause of the missing worker or documenting the required configuration.

Written by the indexing model from the issue text.