A gigabit WAN connection will show the flaws in your home network. When I got Spectrum Gig last Summer, my hardwired desktop PC would not pull in over 600 Mbps when connected to the router, on the rare occasion it did, it could not sustain those speeds. Once I replaced my router, I could instantly get 940+ Mbps like I’m supposed to. I bought the newer version of the router I had and all was good.
Wifi is not important to me, In fact I hate it. Nothing beats a hard-wired connection. Unfortunately, you can’t hardwire a Google Home, Amazon Echo or any other spying IoT device. If it were not for my IoT junk I would not have wifi in my house.
My personal laptop is hardwired, it’s only an is N only, not AC. My work laptop is AC and I can get 350 Mbps on 5GHz at the kitchen table, which is the farthest point in the house from my access point, or 500+ Mbps when at my desk right next to my AP.
On a smartphone or tablet an app like Signal Spy is great, I use competing apps, but they are all helpful. I use the paid version of Network Cell Info for cellular signal strengths and the paid version of Network Signal Info for wifi. At work when I replaced all of our WAPs, I purchased a license of InSSIDer Office from Metageek and used the corresponding app on my phone to map out where I wanted to place access points. Also if you have a Windows device you want to test, you can use the command netsh wlan show interface to view the signal strength percentage.