Mike is worried that his WiFi network is compromised since his encryption was bypassed. Leo said that WEP was hacked, and routers went to WPA. And then WPA2. But the latest news is that "Krack attacks" have gotten into WPA2. Leo says it's largely sensationalized headlines and that it's very hard to do and requires a lot of time being on the network itself. Also, by now, most routers have been patched against Krack. So it's not really anything to fret over. And WPA3 is on the horizon, with new routers turning it on with a software upgrade.
Here are some things you can do:
Use 5Ghz. It's not as popular, and most hackers can't see it from the street since it can't go through walls as 2.4Ghz does.