Thank you again but of course I used the password under the router ..... but they dont ask for the UN ......

So I contacted my ISP (TIME) who provided the router

A technician came to my place, and he could access the router without any problem with his laptop after keying in UN + Password .....

Nothing worked with my laptop (3 different browsers - cable or wifi) and/or my smartphone only my password is requested and not the pair "UN/password" .....

The technician told me he never saw that and that the only possibility was the difference of language configuration between the router and my laptop  (Malaysian ISP, French Windows and Android). How can this be possible ? any clue please ? if it might be possible what kind of solutions would you recommend please ...

This cant be possible since 2 weeks ago i could do it 1 km from where I am now with my hardware and with another TIME router using TIME internet

The technician signed his report after stating that it was not the ISP responsability ......

Believe it is due to your Windows Keyboard layout.
As we normally use EN-US keyboard layout.

Suggest trying changing your Windows keyboard to EN-US then try the said password again.

so just try using a local friend's laptop / smartphone. or bring up a VM with english windows and try accessing your router from within that VM.

bonne chance!

Basically ISP only provide pppoe credentials for our record keeping in their service report. But today the latest TpLink has been controlled by them also, like hongli suggestion, get a new and custom router.