GUI login issue

We all have issues logging in every time to observium, doesn't matter which browser or which OS we use.
When we were logged in before, on the next day or when changing locations and the client ip changes it doesn't work anymore.
If we open a new private browser window it always works then, but not in the standard mode.
Is there something up with cookies or caches?
We can't authenticate unless we want to blow away all the caches to make it work again.
Is there something we misconfigured on the observium or webserver side that causes this issues for us?
thanks, Alex