Lucky for you, i'm very experienced with them.
1. Open your internet browser, whether that be FireFox, Opera, Internet Explorer or something else, just open one.
2. Type 192.168.0.1 into the address bar, and you will be prompted to enter a username and password. The defaults are as follows:
Username: admin
Password: sky
3. Click the Security tab, next click Services. Now click add custom service.
Here are the details:
Name: RSPS
Type: TCP
Start port: 43594
Finish port: 43594
Click apply.
Now, that's the service created, now we need to assign it to a computer.
4. Click the firewall rules tab, which is also within the security tab.
Add an outbound service.
For the service field, find the service you created earlier.
For the action field, select Allow always.
For Lan users, select Any.
For Wan users, select Any.
For Log select what you feel is right.
5. Now go back to firewall rules and add an inbound service.
But, before we start, click the Start Menu, Click Run, Type cmd, and then type ipconfig into the command prompt, do this on the computer you're going to run the server from!
This will give you the "Send to lan server" Field.
Note that number you get down, it should be similar to 192.168.0.x (x being a number).
Once again, select the service you created earlier.
For action, Allow always.
Send to lan server is the value you got from the ipconfig.
Wan users is.. you guessed it, Any.
Log is again, whatever you like.
Then simply run your server.
However, be aware that creating your own client is illegal, however, creating and running a server is not illegal, as you use none of Jagex's resources.
I found (Have now given up on private servers), that Sky does not host them at all. In the 3 months I had my dedicated server, I ran into much less problems.
However, It's still better than nothing.
Good luck!
PS - It'll slow your internet down to a crawl.
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