Hello Tom,
Sounds like you are doing everything correctly, first let’s get your phone updated to IOS 14.5.1. Along with verifying you have the latest version of iPrint installed.
Then you will want to power cycle your Wireless access point; cable modem combo; wireless mesh. Now attempt using the iPrint app on your phone to find the printer.
What are you using for wireless access, are you broadcasting both 2.4 and 5Ghz, Are they named the same?
Once I have some more information I can better assist.