Wifi password not being stored

Hello

I have an iPhone 12 Pro, iOS version 16.3.1.

I am experiencing a problem with my phone not remembering my home Wifi password. I either type the password in or use the share password feature. Whilst I am still in the coverage area of the network there’s no problem. However, when I leave the coverage area and then return the iPhone doesn’t automatically join.

The screen shot below shows the relevant screen. Note that Auto-Join is selected and there is no greyed out password below “Forget This Network”

I have one other Apple device on the network and my wife has three including an iPhone.

Does anyone have any ideas why I have the problem?