@Giacomo_Lanzi I haven’t seen this issue before, so could you check the console in chrome by using the inspector?
Usually there is more information in the console to why its not working. What could be the reason possibly (no experience);
Its a subdomain
You have a plugin blocking the connection
You have a firewall, plugin or some other security blocking the IP
Subdomains: I connect subdomains with the same method without problem, so I don’t think this is the issue here
Plugin: Test has been made activating the Integromat plugin alone, therefore I would exclude this hypothesis
Firewall or ip-blocking: I don’t use a firewall for that website (it’s the one I use to execute tests) and I have been trying from different locations, therefore ip-blocking shouldn’t be the issue.
Another note: connection works for the main domain, so I would exclude some sort of server-block issue.