Q: Forget WiFi not working - keeps reconnecting

HI,

I have been having this issue since several iOS 9 versions up until now (9.3.2):

whenever I connect to a wifi network, I cannot forget them permanently. Forgetting a WiFi might work for a couple of hours, but later all my iOS devices will convert to the forgotten wifi again. Resetting network settings did not solve the problem.

Amy ideas what I could do to solve this?

Thanks!