Why isn't port forwarding working?

Im trying to host a rust server, i have a optimum modem + router connected to some tp link deco wifi mesh thingies. I am trying to open port TCP: 28015 and UDP:28016, i try and open them in the deco app, and everything seems to go through, but the ports are still closed, other people cannot join the server and if i go on any website to check ports the ports are closed. What is happening? What do i do?

I apologize if this is the wrong subreddit