Trying to map a port with 25565 or any

[padnar]

i press the + button i put in 25565 press add mapping and it just doesnt map it says "unmapped" with a mean read dot next to it, it works at my grandparents house for some reason but not at mine. things i have tried: turning off and on again, reopening the app, restarting my computer, restarting router, deleting mapping and making same new one. nothing has worked and i have NO idea why it isnt. thanks for reading