Having trouble with ports/firewall - Linux

[Plorine]

This is an edited post since I've fixed my previous problem.

I've been running a Windows server for a few friends and it's been fine, but I also use the computer to also play Ark and wanted to ease the stress a bit by putting the server on my Linux machine, I've installed it fine, I've forwarded the ports (27015 / 7777 UDP) and added the rules to firewall via GUFW but to no success. I am able to see myself on LAN as expected but I cannot be seen from outside.

I have also tried increasing the port range (27015 - 27017 / 7777 - 7778) since this was listed as a fix in several other boards but this has made no difference.

I am a bit of a Linux noob so bare with me, any help is greatly appreciated and if any more information is needed just let me know and I'll post it ASAP

[panacuba]

Im just a linux newbie, but I might be able to help just a lil.

What version of linux are you using to host your server? is the server up to date with the last apt get?

[Plorine]

Thanks for the response.

I'm running Linux Mint 17, not entirely sure how exactly to find what base distro it's running since I'm a bit of a Linux noob too but I presume it's Ubuntu 14? only method of finding the distro that I know is lsb_release so if there's an alternate way I'll do it if it's important.

I do not know what you mean by updating the server via apt-get? do you mean apt-get update? if so, yes I am all up to date and the ark version is up to date also, all files validated but the error persists.

[Plorine]

Updated OP with a new problem.