Forwarded ports don't appear to be open.

I've been hosting servers to play with my friends for many years and I've never had an issue with port forwarding until now.
A few days ago I went to open 4 ports for my server on the app. I selected my computer from the dropdown list, selected manual, picked TCP and/or UDP(whatever the server needed) and the port numbers. When I hit next it sat there loading until my phone autolocked and I had to start over, I did try keeping it awake but after 20 mins still nothing. The next day I try again but now I didn't see my computer on the dropdown list, which is odd because my computer is plugged into the modem via ethernet cable. I did see that some of the ports I forwarded the previous day were listed as open but when I use multiple port checkers the all say the ports are closed.

So Why are ports that listed as open not open?
and Why don't I see my computer on the devices dropdown list when it's listed as connect elsewhere in the app?