Phone not working in parts of my apartment

Hello

I have a Samsung Galaxy S21 phone and I’m on the 5G network with Koodo. I live in a small 1-bedroom apt in a highrise building in downtown Toronto and strangely, my phone doesn’t work in parts of my living room which is small. It doesn’t work in the kitchen/dining area and sometimes doesn’t even ring.  I only know if someone has called me if they leave a voicemail.  In the living area, my voice cuts out depending on where I’m sitting. I have to sit in an armchair close to the balcony to have a conversation. The apt is only 650 sq ft and it’s ridiculous that I don’t get signal in parts of it. 

I’m wondering who I could talk to and if anyone else has experienced this problem. I would appreciate any thoughts on why this might be happening. I don’t have any problems outside of my apt.