wow 3.3.5 server -> stuck on authentication after new router/modem 2in1

[ragebox11]

so yeah i am starting the server everything is fine somehow... but i suppose that i am having trouble identifying which ipv4 address is my local one... when i go to CMD -> ipconfig -> it shows me an ipv4 address that is the same as my external ipv4 address aka my IP address... i have tried in my router to port forward the ports with local ip the same ip as my ip BUT i also tried forwarding them with some DEFAULT GATEWAY ip... that is similiar to my ip address but is a bit different and i supposed that it was the thing that i was looking for(aka internal ipv4 address)... but it seems like it still does not work for others to connect.

they are stuck on "authenticating"

so ehh yeah... i even edited the C:/windows/system32/drivers/etc/hosts file

so ehhhhhhhhh yeah any help? maybe help on somehow how to find the internal ipv4 address or... is it cause of the router/modem that it like a modem and a router in one
my router says that it's model is called: "TC7200.U"

however based on the information about the default passwords and logins... it seems like it is either: "7230s" or "TC7210.dNZ"

based on its looks it looks like a: "TC7200-U" or "TC7200"

hopefully that info helps.