@JRBusiness110,

I'm sorry to hear that unexpected things are happening. If you detail what you think may be happening, I can try to ease your concerns if it was nothing. Otherwise, I am going to need some more information regarding what your current network setup is. But to start off, I would take these steps to  secure your current network:

1 - Reset Your Network

If you believe that an intrusion has occurred, perform a factory reset on both your modem and router, this will disconnect any devices(known or unknown) that were connected to the router. If there is evidence of an intrusion please be sure to run an antivirus and make sure that your computer is secure before connecting to the new network.

2 - Configure the Spectrum Modem

If you received a modem that provides an internet connection from Spectrum, it is recommended that you disable the wireless functionality through the modem settings. This is sometimes referred to as Placing the Modem in Bridge Mode.

3- Connect the Factory-Reset TP-Link Router to the Spectrum Modem

Continue with the Default Setup using the Login information on the bottom of the router. If you are not logging in with a TP-Link ID, please make sure to change the default username and password to ensure maximum protection.

4 - Configure the Wireless Security Settings.

Set a Strong Wifi Password, and Choose a Security Method, such as WPA/WPA2 Personal

5 - Extra Security

If you believe that another external device has connected, you can monitor the client list on the router to see if any connections occur. There is also an option to configure a whitelist or blacklist that will prevent specific devices from joining the network without your permission/knowledge.