I use an old AirPort Extreme to provide WiFi in my home. It provides a 2.4 and 5.0 GHz network with a good password, only available to me and my wife. It also provides a separate guest network without password. The benefit is that visitors can have WiFi in my home without needing my password so I don’t need to hand my password out.
Question: Does the ability of a stranger to connect to the guest network put my password protected network at risk? Of course they can cause mayhem on the guest network, but would my main network using the same router be in danger, actual or theoretical?
PS. Thanks for all the answers. My plan was to enable friends and family to use Wifi, but not giving them a password which would be dangerous if one of them is a hacker, more dangerous is one of them is careless and gives the password to a real hacker, and inconvenient because changing the password is a pain if a friend becomes an ex-friend.
Apple has a feature where your phone can send the password to another phone if you allow it, so that phone can connect to your network, but the user cannot find out the password. Small improvement.
So the problems are: Anyone near my home can use my WiFi (I've heard a claim that someone in an apartment block could see 37 networks on their Mac!!!, so you could have 37 people able to log in). Not that big a problem because I can throw them out, but still. And the other problem: Someone who has access to an actual network on my router, meaning my router has to process their network traffic, may have more access to vulnerabilities in the router than someone who just parks their car near my network with nothing opened.