I've had my 4g/5g modem + antenna for a while on my roof. It's almost flat, metal sheet roof. Then I moved temporarily the antenna on my balcony that's surrounded by walls from 3 sides and it looks like noise and other signal parameters are bit better. This is in the city.
The antenna is in the middle of the roof ~1m high, so I guess there's some amount of reflection. It's also noisier up on the roof.
I was wondering how much of an impact the roof has on the signal properties?