Go to Advanced > Wireless > Basic Settings and you can choose channel here:p

V1.1 = V1, but you should paly attention to the EU, UK and US version.

After the reset, did you login your cloud account on the Kasa app? If you successfully login, and the smart bulb has internet and with remote control enabled, should be able to see it.

Reset the router. Login from another computer. Disconnect the router from your modem first.

use the latest version of kasa and update firmware of your plug

what device do you connect the main deco to, a modem? did you open some ports for a certain server in the network that you want to access it with the domain? and also check the IP address that your...