Internet keeps cutting out

For the past week and a half, my internet has been cutting out randomly and then coming back 30 seconds to a few minutes later. Sometimes I have to switch between my two networks to restore internet access. Today it has happened 8+ times, even after unplugging my modem, checking that the cords attached to my modem are secure, and ensuring my modem isn't overheating. What else can I do to fix this issue? Sometimes when my connection is restored I get a message in my browser that my internet connection isn't secure or that it isn't private. ETA: I have my own modem, and it is five years old at this point, if that information helps.