Friend cannot connect via IP, can connect via Steam

[Notso]

Hey guys,

Until two/three days ago, my friend (who lives near Washington DC) has been connecting to the server I host for us using my global IP address just fine (I live in Cape Town, South Africa). Now however, she is unable to join the server that I am hosting via IP, but can join via Steam. This would be fine, but joining via Steam causes her to lag like nothing I've ever seen, and basically makes the game unplayable for her. Strangely, I can connect by IP just fine to a server she hosts (but her laptop is rubbish, and can't really handle hosting and playing simultaneously).

I have done a system restore, disabled firewalls on both my PC and my router, restarted my router, double-checked port forwarding etc. etc., but all to no avail. I am reasonably certain the problem lies with my router or my ISP (although I am pretty incompetent with this stuff), as I have successfully pinged her global IP, she cannot ping my global IP, and I have successfully pinged my PC's local IP from another laptop on the same network. Beyond this I am really not sure what I can do to fix this problem

Thanks in advance for any help,
Notso

Spoiler: My specs

Windows 10 Home (x64)
ASUS Maximus VII Ranger
Intel i7 4790K
MSI GTX 970
Thomson Technicolor TG589vn v3 (router)
MWEB (ISP)

Spoiler: Her specs

Late-2011 13'' MacBook Pro (link)
Fios Quantum Gatweway G1100 (router)
Verizon Fios (ISP)

 

[Marcus101RR]

http://portforward.com/english/routers/port_forwarding/Technicolor/TG589vn_v2/PS4.htm

You will want to DMZ your LAN IP.

 

[Notso]

http://portforward.com/english/routers/port_forwarding/Technicolor/TG589vn_v2/PS4.htm

You will want to DMZ your LAN IP.

DMZ my LAN IP?

(The article you linked seems to be about port forwarding... Which I have done)

 

[Marcus101RR]

DMZ my LAN IP?

(The article you linked seems to be about port forwarding... Which I have done)

You will need to find the option to DMZ, its in every modem/router.

 

[Notso]

You will need to find the option to DMZ, its in every modem/router.

That's all very well, but I have clicked on literally every menu and still can't seem to find anything called "DMZ" /: Might it be called something else? Again, the article you linked to was about port forwarding, idk if that is the same thing..?

EDIT: I found the DMZ settings squirreled away deep in a menu somewhere, and enabled it for my PC (I think, I can send a SS if you want), but we're still unable to connect. I presume we should still be using the IP address I see when I type "my ip" into Google?

UPDATE: Neither of us are sure why, and neither of us know what's changed, but she can finally connect, so yay, praise the IP deities etc etc, thanks for your help Marcus!