Remember that you have to save and reboot your modem for these changes to take effect.
Make sure that your “Internal Host” IP is set to your ipv4, open a command prompt and type
ipconfig /all to find it (I’m not sure if that’s correct since your modem also asks for your PC Name, kinda redundant…). also increase the range a little bit, go from 24800 to 24872.
after doing that, launch citra and create a room, you should be able to create a room even if your port hasn’t been forwarded.
after doing that you can check this website for the port 24872, it should say success.
it does not show since citra uses only UDP and it checks open TCP.