iPhone 7 Wifi issues

Why does my phone only work if I have an active SIM card in it (only because of data)? The wifi randomly disconnects. It works every now and then. The phone does not work on wifi if an active SIM card is not in it. And even when the SIM card is in it, it still works only when it wants too. Sometimes the wifi setting is even stuck on “off” and cannot be turned back on. I have reset the network settings, I’ve even hard reset the phone multiple times to see if that would fix the issue, it did not.