Modem and Router? - moving away from combo

Hello!

Super appreciate of getting advice from you guys! I have Xfinity internet, and I have used a 3.0 Motorola Combo. Looks like it has conked out, and it is now my opportunity to improve WiFi in my 1,600 square home in a building. I live on a tight budget, so trying to find the best I can find for a small budget. This is where your advice comes in super helpful! What should I buy? Please help a newbie in improving connectivity at home for a few phones, iPads, laptop, computer, Nest, oh, and yeah, my tv with streaming services.