Since some weeks I have a very strange problem with wy tp link router

It took me a long time to realize that it is linked to the use of my tp-link wifi. 

Here is the situation:

- when connected on our tp-link wifi, all our smartphones (3 in total) and tablets (2 in total) work well to surf on the internet, play video games, look videos on youtube, make visioconferences, etc. but it is impossible to upload any app through the google play store. When we try to load an app, the loading seems to start, we get the message "En attente" (in french. I assume english tranlation in "pending"), but the loading never progresses and after a minute we get a message saying that it is impossible to load the app.

- when connected to another wifi or to the 4G, the same smartphones and tablets have no problems and we can load applications through the google play store. Note that I need to empty the data and cache of the google play store app after having switched from the tplink connection to the other connection.

Any idea why we can't load apps when connected to our tplink wifi?

Thanks in advance for your help!