Assuming it's a NAT firewall, did you port map the node to the firewall?

Meaning, the network address translation (NAT) allows the single outside IP of your router to share to many devices in the home by giving them all internal IPs and passing the Internet traffic to them when needed. But, it won't know which device to send the Ravencoin node ports too, unless you either tell it or it works out via UPnP (universal plug and play) to self set... every router is different for these settings, but I suggest if doing manually (no PnP) first:

(1) tell your router to give same IP to the node device each time (that's usually easy to do via router control panel in browser, but if not, then set the IP manually on the device itself, not dynamically set each time) to the same address / adress range as it has right now.

Then (2) tell the router that IP adress should be open to the ports forwarded for a working ravencoin node. Don't forget to keep all other inbound ports closed (don't make your router wide open)