Am I using 2.4 or 5GHz

Yes, but not as much as you might think . Most bedroom doors are made out of hollow wood, so they don’t restrict the waves of wifi too much. Opening the door will free up space for a smoother signal, but it might not be much more since the door isn’t too much of a factor in the first place.

The 5 gigahertz signal (Wi-Fi a or AC) accommodates more devices at higher speeds, but reliably passes through only 1 or 2 walls and floors . Naturally, distance, placement and interference are also important factors.

Most WiFi can travel about 50~75 feet in a home or about 150 feet in open air. But 5G WiFi is 10~20 times faster but can only travel about 25~50 feet indoors . Faster-but-closer.

5 GHz networks do not penetrate solid objects such as walls nearly as well as do 2.4 GHz signals . This can limit an access points reach inside buildings like homes and offices where many walls may come between a wireless antenna and the user.