WAN connectivity failure every 5 minutes on Technicolor router

I suggest you to turn off the 2.4 GHz wireless network named TC8717T88 on your router. Then your Automatic location will stop magically switching from one to the other wireless networks, thus having the valid IP for the other network (which doesn't fit the DHCP lease of the actual one).

You will be able to change this from a perfectly connected computer (ideally through Ethernet). Open your web browser, and connect to your TC8717T router with:

http://192.168.0.1

login:          admin
password:       password

goto:

Gateway > Connection > WiFi

click:

EDIT

Configure as disabled the "Private WiFi Network Configuration (2.4 GHz)". Configure on Manual channel choice the "Private WiFi Network Configuration (5 Ghz)".

I made the hypothesis (which is quite often the case) that your 2.4 GHz is overloaded and sometimes subject to access failure due to interfering neighbours network. Then by forcing your connexion on 5 GHz and a given channel you will get a stable one, without anymore dynamic IP renewal.