Honestly, I'd get a professional in to run a wireless survey otherwise you're going to be chasing your tail and trying to tweak settings left, right and centre. The cost of which would cover the survey.
Darren OConnor | doconnor@resalire.co.uk
https://www.linkedin.com/in/darrenoconnor/
I'm not an employee of Cisco/Meraki. My posts are based on Meraki best practice and what has worked for me in the field.