What do you mean by your own computers? Do you mean that you can see the dashboard on a computer that is not running node-red?
Assuming that you can see it on one computer on the network (that is not the one running node-red) then you will be able to see it on any computer that can access the one running node-red. Usually that would mean any computer on the network, but if you are on a network with multiple subnets then it depends on how the network is configured. Also it is possible that the computers are configured with firewalls to prevent them from accessing the one running node-red, or your firewall is configured to only allow access from your computers and not others on the network. If you are on a corporate network you would have to ask your IT department about that.
You will not be able to view it on computers that are not connected into your network. If you want to do that then you have to be very worried about security, as you want to stop hackers from hacking into your system. If you do want to do that then talk to your IT department first. If you are not in a company environment then read this FAQ post for advice on how to safely access node-red over the internet.
