Poor Signal Midwestern Ontario

That is a very hard question to answer, given that this is territory served by Bell, Telus and Rogers. All I know if that the signal, which has always been LTE since the tower was erected a decade or more ago, is now no better than 3G on the south orientation of the tower, south of Maryville Lake Road. North of the tower it jumps to 5G.

The tower is located just east of Bruce Road 13, not Bruce Road 8, on Maryville Lake Road in South Bruce Peninsula. The land south and west of the tower is also Saugeen First Nation and is heavily populated with summer cottages on the Lake Huron shore. It is the largest recreational land on an indigenous reserve in Canada with over 1200 leased properties. Not all, of course, are Telus customers. The standing joke has been that you always knew who was another cellular provider (not Telus) as their customers stood out in the street to use their cell phones. I have never had to do that as a Telus customer. 

My phone is an iPhone 15 Pro, with iOS 27 Beta 2. The other iPhone has iOS 26. Both are set 5G ON. 5G Auto and 5G On in Settings makes no difference in the cellular reception. A business iPad, with a Bell cellular account, does connect at LTE. It always has. Not the iPhones, however. 

I recognize tower crowding may also be an issue, but that has never been a question previously. Neither has terrain nor leaf foliage, which can affect cellular signals.