What is the make and model of the phone you are experiencing the problem with?
Did you do anything so far to try and troubleshoot the problem like maybe putting your SIM card in another phone and see if the problem goes away?
Welcome to the community!
What phone are you using (were you using)? Have you verified it has the neccessary compatible bands/frequencies? You can verify those bands/frequencies here.
Have you verified the phone is using the proper APN settings? Assuming it is LTE-compatible, it should be using ltemobile.apn. You can verify those settings here.
It sounds like you were experiencing call drops and poor reception at your location prior to getting your new phone as well. Have you verified that your area is adequately covered by Fido/Rogers? Cellular coverage is dependent, in part, on your location relative to the surrounding cellular towers. You can get an idea of your area cellular towers here.
Are you able to manually select a different network? Extended coverage is generally available in areas of weak or poor Fido/Rogers coverage but within another provider's coverage. If this is your situation, I would have expected your phone to automatically connect to Fido-EXT. However, you might be able to manually select Fido-EXT if your signal is rather poor.
Are you able to try a different SIM in your phone? Are there people in your area with adequate cellular service?
Hope this helps