Error 504 during Let's Encrypt certificate generation

[a107480098]

Hi,

I'm trying to use Let’s Encrypt on my server but, after a long wait, VestaCP goes off and I receive a "504 Gateway Time-out".
After that, I have to restart the Vesta service.
I tried to uncheck "SSL Support" before apply Let's Encrypt, also deleting any alias (www.mydomain...)...

Vestacp: A new installation. Default installation
VPS configuration: 2 CPU cores Shared, 2GB Dedicated RAM
System: CentOS 7.6.1810 (x86_64)

How can I look further what's going wrong ?
Any help? Thanks!!