Thanks for reaching out.
Google Nest Hub isn't officially launched in Poland, so it may or may not work. A few questions: what's the exact message you're getting when connecting it to your Wi-Fi? Was it connected or working before on the same network? Also, is it within 15-20 feet of your router?
Give these steps a try:
Looking forward for your response.
Checking back in if you still need help with this? I'll be locking this thread if we won't hear back from you again in 24 hrs. Should that happen, feel free to create a new one if you have more questions or have other concerns in the future.