After many years of consistently getting 4 bars, over the last few months the signal is 1 or 2 bars. I live 200 yards from Verizon's tower but now get spotty service. The weak signal has been over the last few iOS updates (currently 15.7, I have not moved to iOS 16). Do I need to replace the SIM? Although the phone is an older model it is still supported by Apple. How do I get back to consistent 4 bar coverage?