[1.6.1.24] Unable to connect to Prestashop Addons on a new shop

[Abacchus]

Hello dear PS community 😎, it's days that I'm trying to solve my issue. Hope someone can give me some hint ! : 

I've just duplicated a PS site [1.6.1.24] for a new domain.
 
The original site works perfectly: from the admin, I can connect to Addons to make updates.
The copy works fine except for the addons: "Prestashop was unable to connect to Addons. Please check your login and Internet connection.
 

-The 2 sites are on the same host (O2switch - but with 2 different DNS)

 

I've done a lot of testing 😅 : 

 

-I tried connecting with different browsers to get rid of the cache problems (each time on the 2 sites to be sure)

-I connect to my Addons account https://addons.prestashop.com/ ... I discovered a new interface (yellow and black) with the possibility of adding a store (https://addons.prestashop.com/fr/agency-shops.php) , which I did. 
 

-I also tried to create an entirely new  Addons account : same issue...

Nothing works with my new store, I'm stumped! 

When I press the CONNECT button , I always get the following at the console: 

https://dev.vinotheque-tours.fr/adminXXXXX/index.php?controller=AdminModules&token=xxx with the payload "' ajax :1, controller : AdminModules, action; logOnAddonsWebServices, username_addons: xx password_addons: XXX
Answer : KO

I don't know how to interpret this, any help ? 
 

Thank you in advance !