Comment: added the firewall section. not 100% what you'd need to allow through firewall but its good enough

--- 11.md
+++ 10.md
@@ -5,6 +5,9 @@
 3. Send your friends your IP and port, which should be formatted as *IP:Port*. The port your friends need to join may be different depending on if your router provided an "external" or "service" port. If that does not work, then just provide them the original port. 
 *DISCLAIMER:* IPs that start with "192.168" or "127" are not IPs that you send to other people. These IPs only make sense to your router alone, and will not work for anybody other than yourself!
 
+## Everything works, but they can't join my server???
+Make sure to see if your firewall isn't preventing people from joining your server! You can test this by disabling your public network firewall. Instructions for Windows systems can be found [here](https://support.microsoft.com/en-us/windows/turn-microsoft-defender-firewall-on-or-off-ec0844f7-aebd-0583-67fe-601ecf5d774f). If you don't feel comfortable disabling the entire network, you can allow ORRH and the various clients you want to host to bypass your firewall.
+
 ## I'm not comfortable sharing my IP with the numbers on them!
 You can use [noip.com](https://www.noip.com/) to change it to a random domain! It will still redirect to your IP.
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