You're most welcome, Lilmil. Always happy to help.
Basically, an Ethernet cable is what you'd use to physically connect your modem router to your computer. You most likely have one that came with your unit. You'd simply plug one end into an Ethernet port on the back of your modem router, and the other end into the Ethernet port of your computer. Following that, you may access your modem router's interface. The method for doing so varies with make and model, but is essentially a similar process for most. Refer to your modem router's manual for details. From there you may check the wireless configuration settings and make any necessary adjustments.
Feel free to reach out for more assistance if you get stuck.