"Connected without internet" when switching between AP's with same SSID, untill i turn wifi off and on again

I have a KPN wifi router in my living room and a TPlink wifi "mesh" extender near my kitchen. Even tho i cant use it as mesh since theyre different brands.

When i leave to my kitchen, the WIFI signal of my router is still present, but very weak. Ever since adding the extender and having set it up with the same SSID, my phone switches between the AP and my living room router seamlessly when one becomes stronger than the other.

However it only was like that for a week.

Now, when i walk to the other room, my phone still switches, but less quickly. And when it does, i always get "connected without internet" after a while. I am connected to the closest WIFI AP, only when i disable wifi and turn it on again on my phone, will i get internet access.
When im in this "connected without internet" state, i do have access top all my devices on my local network.

The fact that it was not like that at first, makes me utmost confused. I have not changed any settings ever since setting it up.

I tried hard-resetting bot the AP and my router, same issue still persists.

My laptop does not have this issue, its only my phone