Ok, so an update: i connected the second bulb that i bought to the coridor (further from the router), somehow this one connected to the app and works. The other one, which is closer to the router does not.
My ISP does not block any traffic, and given the fact the other bulb works, it is not realistic.
This is obviously some fault within the product. Is there any actual solution to this? I see on the internet there are a lot of people with similar problems. Why can't you issue a fix or a guidance how to solve it? I am very disappointed with this product and will not buy again.