I'm unable to get my server to allow connections outside my network. I understand that it might be a port forwarding problem, router firewall problem, or an OS firewall problem.

A few things to note: (This is copy and pasted from my server config)
ip="0.0.0.0"
port="28015"
rconport="28016"
appport=28082

When I check "canyouseeme.org" they say that my 28016 and 28082 are visible. However the 28015 is responding with "connection refused".

I have tried to use the port 28017 as well with the same problem.

My router has 28015, 28016, & 28082 port forwarded for TCP & UDP.

All of my firewalls are disabled.

I CAN connect to the server in Rust via "connect localhost:28015" (from the Host PC on my network)
I CAN connect to the server in Rust via "connect [Internal-IP]:28015" (from another PC on my network)
I CANNOT connect to the server in Rust via "connect [External-IP]:28015" - Error: "Disconnected: Connection Attempt Failed"
I CAN see the server in the server list, but I CANNOT connect to it.

I've tried this on Windows 10, Linux, & multiple computers. I have not tried different rounters.

I've followed every tutorial imaginable. Please help.
Thanks in advance.

The main game port (28015) is the only one that runs on UDP. It seems like you've covered all the bases and you know what you're doing, so could it be that UDP is being blocked by your ISP?

Merged post

Or maybe try forwarding UDP only for 28015

see if your ports are open to systems not on your local network using this tool

https://www.yougetsignal.com/tools/open-ports/

and try temp disabling your firewall/internet security programs to see if they have blocked it.

Merged post

just thought of another thing... make sure the computer that's running your server has a static IP.

https://portforward.com/networking/static-ip-windows-10.htm

you may have set port forwarded correctly but upon reboot, it may have obtained a new IP.

I was assuming that your Rcon port was working fine from the outside which is why I suggested the UDP thing. If nothing is working then "check your external IP" is a good call by nashslash