I cannot reliably connect to home Wi-Fi network, regular error I receive is 'network temporarily unavailable.'

The simple fact is that you have no problem with other networks which suggests your iPhone hardware is not defective. In other words it is either a settings and configuration problem or possibly electrical noise (interference), or maybe a problem in your WiFi router but this seems unlikely because other users have no problem with it. That brings us back to settings or electrical interference!

I think you need to explain a little more about your WiFi setup, including (but not only) what type of router (make/model) and the general layout of your nome and router location. (I'm thinking possible signal blocking or electrical noise to where you lose signal). All clues will be gratefully received and might help us guide you to a solution - but just be careful not to reveal any sensitive data like passwords or human names.

The other question... how long has this been going bad for you? Is it a new problem, or longer term, or has always been flaky since the phone and WiFi first met each other?

How many devices connected at one time to your home WiFi? Have you done any troubleshooting with your WiFi provider and/or the manufacturer of tne router to ensure those settings are what they should be? Any restrictions on what devices get priority?