When you can access a URL on a computer but can't access it on another computer, it's almost always one of 2 reasons:
1. The address you're using to access the computer from isn't resolvable. Meaning you need some sort of DNS service to translate the URL's domain/host address to an IP address. If you're using the actual IP address, this isn't an issue.
2. You have a firewall blocking the port(s) you need. The firewall may be in the computer you're accessing or in a router or other device that stands between your client and the target system.
You CAN also have a problem if there's no actual network path from the one computer to the other, but that's less common. You can use "ping" to test for that, assuming that the target doesn't have ping response disabled.
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