After a power failure, it takes several minutes for the modem and router to get the connected again. Please note the router and modem lights when all is working okay and then again after a power...

Try using the TP-Link's Tether app. Not sure if you can control the guest network for you model but appear I can with my Archer C8.

Okay, you have a power failure, How long do you wait to see if the connection is re-established? What do you do to reset? Could it be that your modem or ISP that is taking a long time to reset?

The version number should be on the tag on your router. As far as your guest network goes, be sure to page down to the bottom of the screen and click "save".

If you are in the US keep the US model. If in CA keep that router.

If I understand, you connect the modem to the yellow connection of the router and you are not getting any internet. Try connecting a PC direct to the modem with an ethernet cable and see if you have...