iPhone 12 Mini - intermittent alerting

[Frog Hollow]

iPhone 12 Mini, IOS 15.5 128GB.
This has been happening since new. Phone ringing, SMS alerting, Timer alerting and other Apps that produce an alert. Sometimes there is no aural alert. The function works but fails to sound the alert. At other times it all works as expected. I have tried variations of Sounds and Vibration patterns/Notifications to see if there was link between them and the App but it persists.
Ideas on how to diagnose the issue?

 

[NSquirrel]

Going from your description, this sounds similar to our iPhone 8s and out old iPad. In 4 or 5 years, I forget how old the 8s are, we have never found a solution and I assume it is some bug in all the versions of iOS I have installed. It can happen if the iPhone is logged in and running, but often my wife will say that she has found an email or alert and not heard anything, even though the phone has been sitting next to her. (Btw, it is very easy to knock the switch on the side of the 8s to mute the sounds.)

 

[Frog Hollow]

OK- I have narrowed this down to what I think is 'normal' operations. When the phone is linked to the iwatch I do not get the 'normal' alerts on the phone. Can someone give me the 'idiot's guide to setting up the watch/phone combination so that the phone always sounds/vibrates the alerts whether the watch is linked or not. I am quite 'hard of hearing' and usually have everything set to maximum volume. Following that is it possible for both the watch and phone to sound and vibrate alerts at the same time. I haven't found an answer to the intermittent sounding of alerts yet.

 

[bear7962]

I think its a one or the other thing