Disable wi-fi autoconnect sharing between iPhone and iPad? Absolutely critical!

This has to have been addressed before, but I can find only scattered threads that do not give a satisfactory solution. Help me out!

I need to disable the sharing of wi-fi network login and autoconnect settings on my iPhone with my iPad. I do not want to turn off keychain and lose syncing of web logins.

I am a sound engineer. I use my iPad to connect to the venue's mixing board (via the board's built-in wi-fi network) and control sound levels remotely as I walk around the room.

I connect my iPhone the the venue's internet-connected network to enable access to web and email.

Once I log into the internet wi-fi network on my iPhone, I am at risk for the iPad to suddenly connect to it as well - I lose control of my sound board in the middle of a show. Not good!

I want to be able to have the iPhone auto-connect to it's network, and the iPad auto-connect to its (different) network, with no possibility of each device obtaining info from the other and connecting to the wrong network.

My situation cannot be unique - this is a work-critical necessity! I don't want to turn off keychain or iCloud completely for obvious reasons.

What is the solution?

Thanks, JW