Why does the Lumia 830 have a weaker signal than the Lumia 635?

[Windows Central Question]

I bought the AT&T Lumia 635 in January and it had a somewhat decent connection where I live (not quite in the city), I was able to use it in my home/room and could share the mobile data to my laptop as well. A few days ago, I bought the AT&T Lumia 830 and it doesn't have any signal in most of my home, or at all in my room. What could cause this?

 

[hotphil]

Three possibilities:
​1) The signal has weakened from the cell tower

2) The signal is the same, just indicated differently on the new handset


3) The new handset's design doesn't connect as well as the old one