Minecraft home server

Okay, i think im being mind fucked, but i use to host servers for me and some friends on my computer, i had no problem with portforwarding except my internal ip would always change, but recently ive been port forwarding but the port wont be open (id check canyouseeme.org on port 25565) but no matter what i tried, it wouldnt work, so i tried setting up a static ip, port forwarded it, didnt work...
Then i tried port forwarding on my laptop with my laptops internal ip, and IT WORKED! I dont understand why this happens but if someone knows, please help me out, my laptop is too crap to host a server.
I dont wanna start using hamachi, thats noobie :3

why would u set up a static if if ur ip i changing already?