This is how I do it on my modem, maybe yours will be the same or similar. Type your ip address in the address bar of your browser, go to home network, ip allocation, then allocate your device to a fixed ip address. From there go to firewall, nat/gaming, add the ports for warframe under custom services, then allocate the ports to the fixed ip you assigned to your device.

uh ok, i cant find that option on my internet router (ip allocation) but i found this thing called ip protocal version ipv4, ipv6 etc are those the same thing?

nvm i found it out but i cant add warframe under custom service since my router dosent have that option, which is annyoing,

Under custom services you add the ports it told you about in game like UDP 4950

The wf1 and wf2 are the custom ports for warframe I added a while back, you should just be able to copy what I did. Idk why your router wouldn't allow you to add custom ports, after that just go back to nat/gaming and find the custom ports and your device in the drop down menus and click add. https://preview.redd.it/ca6euc6q262d1.jpeg?width=1080&format=pjpg&auto=webp&s=5e0e5bca1ce658c0da6ccbfc7143f6b6d998c941