my router delivers 300mb when I connect my pc directly with cable to the router. When I connect the AC1200 it not delivers more tnan 100 mb even when I am very close to the tp link unit

I fiound the app TP-Link Deco in Google Play but it is not installed on my Phone Samsung S23 Ultra. I could use it from google play to install my XE 75 pro succesfully but every time I want to do some