Is model # Archer C60? If only your Macbook cannot connect, reboot it. Make sure it's not blocked by the router. Double check the wireless password you enter.

Zyxel c1000z is a router, isn't it? You may connect the C8's WAN port to LAN port of Zyxel, configure C8 as a router as well. Just follow the installation manual to log in and finish quick setup.

Locked like it cannot be updated to third-party firmware? Yes I think so.

The only way to change settings is through Deco App. There may be a web interface soon. Currently the App cannot show whether it's using Wi-Fi Ethernet as backhaul, but it will be available in the...

What's the internet status? Is it connected? What NTP server do you use? With HW and FW info will be helpful.

I used to the app too. I don't have to reboot the router to get it appeared on the app. It's better to contact tplink support directly to figure it out and you could pass your feedback about changing...