It doesn’t matter what you feel, only facts
. Find out what is going on. Is it just a problem when connecting to one of the networks/APs, or both? I assume people have passwords to both, so they can connect to either network. In that case units aren’t assigned anything, in that they can do whatever they want. You need to talk to everyone to try and narrow it down. And have them show you, just like you’ve done tests yourself. If there are only 3 people, go to each one and run tests in each one. You got stuck with the job, you need more info.