You are right, sorry.
I would start with mentioning that I've done the Wifi Setup before and have succeeded. The printer had been packed down for some time and now I resumed my work. Unpacked, and was ready to go, but failed. Maybe the wifi password was changed since last time, maybe something else.
These are the steps I followed
Factory Reset
Wifi Setup > "Wifi Hotspot created, use a computer or smartphone to connect"
It asks me to connect to "UM-001e19" which I do (with my phone)
at this point, I remember I was offered to click or something, that brought me to the setup-page. This did not happen this time.
I enter a random URL like recommended above and ....
OK. I continue this post for the sake of documentation. Even though it didn't work last time, this time it did. Typing a URL I've never been in before brought me to the Ultimaker.
I don't know what was different other than connecting the Ultimaker through LAN, updating the firmare and then trying again.