Wi-Fi booster box Poor reception?

Hello because of the current #how to stay Corona phase I wanted to watch a movie on Netflix on the pc today, strangely only 10mbit instead of 100K MBits arrive in my room / have a 1Gb line from Unitymedia what can be the reason that my internet is so bad?! I have 10 MBits on my PC, but I have 600K on my cell phone over 5G?

On copper cables?
to many other users in your area?
at the limit of Netflix?

I got the 1Gb over fiber

have 2 iPhone's here in the Wi-Fi (5G)

5g is not Wi-Fi…

All of this goes outside to a distributor, including neighbors ect.