Make my home Wi-Fi faster, more reliable, and more secure

Help me improve my home Wi-Fi and make it more secure. The problem: [e.g. slow in the evenings, no signal upstairs, drops during video calls, not sure it's secure] My setup: [internet provider, plan speed if known, router make and model, whether my provider supplied it, how old it is] Home: [size, floors, thick walls, where the router sits] Devices: [roughly how many, e.g. phones, laptops, TV, smart speakers, cameras] Speed test results: [optional - near the router and in the problem room] Comfort with tech: [low / medium / high] Part 1 - Performance: 1. Likely causes based on what I've shared, from most to least likely. 2. Fixes to try in order, easiest first: restart, move the router, reduce interference, switch bands, update firmware, wired connection for the TV or computer, mesh or extender, contacting my provider. 3. When it's worth upgrading the router or plan, and when it isn't. Part 2 - Security: 1. Change the default router admin password and the Wi-Fi password. 2. Use the strongest encryption my router supports. 3. Turn on automatic updates if available. 4. Set up a guest network for visitors and smart devices. 5. Check for devices I don't recognize. Mark router menu names [CHECK IN MY ROUTER'S SETTINGS OR MANUAL]. Never ask me for my actual passwords. Finish with a short checklist and what to tell my provider if the problem continues.