Hi Mattks7,
Thank you for posting in the Apple Support Communities. I understand you’re having problems connecting to your home Wi-Fi network.
From what you’ve shared, it sounds like there may be an issue with your Wi-Fi network, causing your iPhone to prefer cellular data.
"If iOS detects an issue with your Wi-Fi connection, you might see a Wi-Fi recommendation under the name of the Wi-Fi network that you’re connected to. For example, you might see the alert "No Internet Connection". To get more information, tap the Wi-Fi network."
You’ll find additional help troubleshooting your Wi-Fi linked below.
Wi-Fi Assist helps out when you’re iPhone is having problems using a poor Wi-Fi connection.
"With Wi-Fi Assist, you can stay connected to the Internet even if you have a poor Wi-Fi connection. For example, if you’re using Safari with a poor Wi-Fi connection and a webpage doesn’t load, Wi-Fi Assist will activate and automatically switch to cellular so that the webpage continues to load. You can use Wi-Fi Assist with most apps like Safari, Apple Music, Mail, Maps, and more."
I’ve linked more information about Wi-Fi Assist below.
Cheers!