I tried to go back to using an old but trusty iPhone 5 in 2018. I found that I couldn't get a signal in half the locations I used to get signals fine previously. Technology had marched on, and so had the mix of 2G, 3G and 4G bands.

Given that our beige computing boxes used to be out of date within two years, I'd say six years for a phone is good going. Time to get a new iPhone.