There looks like something else is still going on. I have 2x sprinklers in different setups, neither works on the IOS app using a remote connection (http / https + reverse proxy + basic auth) but both work on a local connection (http + reverse proxy, no basic auth). I recently updated my phone to iOS14.4.2.
When setting up in the app a new connection to the https + reverse proxy + basic auth ospi system it reasonably quickly returns Check IP/Port then try again. When doing the same for the http + reverse proxy + basic auth ospi system it times out after about 40sec
For both systems if I take the connection path entered into the app and test in a web browser in iOS, once I get past the basic auth they work fine. App broke some time in the last week for me.