I am using the TP-Link C7 modem and recently updated to the latest firmware 180114. It works fine otherwise. It appears I can ping the other devices on the local net with their IPv6 addresses. However

I have a Deco M5 network that was set long time ago. Because I changed my Android cell phone, I don't have the Deco app on my phone anymore. I tried to reinstall the app. However, it always ask me to