So i have port 5900 forwarding all connections from my external router ip from the website (canyouseeme.org) to my internal ip.
HOWEVER, now when i go to canyouseeme.org, instead of getting the OPEN PORT message, i get this:
Assuming you're using the correct IP address as per plinden's last post, you may want to also check your router's firewall configuration in detail. It may be set to block port scanning (probably in the DoS defence section or similar), which could be separate from your other firewall settings.
To test, I've just set up a port forward on 5900 on my router, but left "block port scanning" on, and got the same time out message as you from canyouseeme.org. I then switched off "block port scanning" and canyouseeme.org found the open port.