Can't create a subdomain named "s1"

Hi, I’m trying to create a subdomain named “s1”, but, even if Cloudflare says it’s been created, when I open it on my computer (with Safari) or on my smartphone (with Internet Samsung), it says it can’t find the server. If I rename it “s” or “vps1” it works, so I can’t understand why it isn’t working with that name.

Whats the domain?

It’s, and I need

The record is there ->

You seem to have some sort of network block in place however. Check your IP access and firewall rules.