Firewall
RR uses the port 7773 for all communication to the rrServer.
If you have a firewall, please open the port on the rrServer.
If you have a personal firewall that blocks outgoing connections (the Windows firewall does not), then you have to open the port on all machines as well.
Windows
The rrWorkstationInstaller adds a firewall rule for you.
If you do NOT want to use the rrWorkstationInstaller and manually configure your firewall, then please follow these steps:
- Open the windows Firewall settings: Control Panel\All Control Panel Items\Windows Firewall
 - Choose "Advanced Settings" from the left menu
 - Click on "Inbound Rules"
 - Right Menu "New Rule..."
 - Choose "Port", Next>
 - Choose TCP and set "Specific local Ports: 7773", Next>
 - Allow the connection, Next>
 - No change (everything checked), Next>
 - Name it RoyalRender, Finish.
 
CentOS 7+ / Linux with firewalld
- This enables it for the current session:
Open a terminal and execute
firewall-cmd --zone=public --add-port=7773/tcp - This  saves the setting that it works after a reboot:
Open a terminal and execute
firewall-cmd --zone=public --add-port=7773/tcp --permanent 
CentOS 6 / Linux with iptables
- open a terminal and execute
iptables -L.
It should look similar to this output:
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED
ACCEPT icmp -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:ssh
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT)
target prot opt source destination
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT)
target prot opt source destination - Take a look at the first section "Chain INPUT".  You have to add a line before the 5th line "REJECT". This will shift REJECT to line 6.
To add the rule to the 5th line, execute this commandline:
iptables -I INPUT 5 -p tcp --dport 7773 -m state --state NEW,ESTABLISHED -j ACCEPT 
- Execute
/sbin/service iptables save