I have a Galaxy S9. The phone keeps switching networks when I use it at home. The reason is that the publc "Cable-Wifi" has a very weak signal. Every time it comes into range it bumps my own wifi. I have switched off auto-reconnect and hot forget network hundreds of times but it keeps happening. The only way I would be able to do it is to stop the phone from scanning networks or block "cable-wifi" indefinitely. Any ideas on how I would do either?