Wifi not working
Since the last few weeks, I am having issues with wifi connections on my iPhone. I can basically not turn it on. The button in the settings is not greyed out but when I slide it right, it immediately slides back left and does not connect. Similarly, from the control panel, it goes blue when I click and then back to grey. This happens about 95% of the time. Then randomly it would work. Sometimes I would even be connected to wifi while the wifi button is off.
I was due to change the phone where this was happening from an iPhone 6 to an iPhone 8 and, to my surprise, I have the exact same issue with the new phone, from the beginning, so I am quite sure is software, as I backed up the old phone and restored in the new. I have tried resetting network settings but nothing improves. Any idea what's going on?
iPhone 8, iOS 11.4