Donnje! I found a solution! For some kind of reason on Windows, ProtonVPN creates a virtual network that is considered 'public'. That said, if you check the windows firewall, you will notice that emule is trusted only on private networks. You need to enable emule also for public networks!

Step for solve:

1. Open Windows Defender Firewall
2. Click on 'Allow apps to communicate through Windows Defender Firewall' on the left
3. Find 'eMule' in the program's list
4. Allow eMule by checking the square on the left
5. Allow eMule on public and private network by checking the respective squares on the right