Confusion over best selection of Wi-Fi channels for 2 devices

In order to extend my wired network and Wi-Fi signal throughout my house, I've connected an older wireless 801.11ac router as an access point via Ethernet cable to my router. Both devices have the ability to "auto- select" the best channels for reception.

The access point and the router have set themselves to different Wifi channels. Is this what I want or should I try to change the access point channels to match the channels selected by my router?

I'm also confused about naming my SSID. Should all devices (I also have a power line extender) share the same SSID? Is there a naming protocol I should follow?

Thanks in advance for any help.

Welcome to the forum. Keep both routers on different channels or they will interfer with each other. You can have all SSID the same but it's better to have them different so you know which one your connected to so you can login to the best one that's closes

Hi Samuria,
Okay thanks for clearing that up. Just to be sure I have this correct, the SSID on each device can be anything I want but I should name it to be recognizable to me for each particular device for future troubleshooting.

As for the channel selection of each device I should probably download a free Wi-Fi analyzer and load that software onto my laptop. From there I'd take the laptop and monitor what the strongest channel is in particular rooms of my house and set the device to function on that particular selected Wi-Fi channel.

Or is the "auto select" feature perfected enough nowadays to let the device decide for itself then and there, keeping the "auto select" feature active for ongoing adaptation for the future changes based upon my neighborhood's usage/activity?
TIA, John