First boot of a MOX: I can ping but no HTTP

I just started a Turris MOX with modules A, B and C.
I first try it without a WAN, just plugging an Ethernet cable between a laptop and the module C of the MOX. Wifi on the laptop is disabled.
The MOX boots (fixed LED, then the blink-blink-pause pattern as documented).
Now, on the laptop, I get an IP address, 192.168.1.136 (so I assume the DHCP server of the MOX works) and I can ping the MOX at 192.168.1.1. I also can talk to an SSH server (but I cannot log in, of course, no password set yet).
But there is nothing listening on HTTP or HTTPS. curl http://192.168.1.1 (or https) replies “Connection refused”. So, I cannot do the initial configuration.
Any idea?

Might be related

I had to restart the process five times to find out that firefox somehow (at least for me) fails in starting the first-boot-process.
When using Microsoft Edge it worked.
As in @bortzmeyer 's case there is no service for 192.168.1.1 running I am unsure it could be related.
@bortzmeyer: Did you use a fresh 7.0 MOX medkit image?

It is a brand new MOX just shipped from Discomp. So, I use the default image (on the flash memory?)

The default image is installed on a microSD-card, you can access it by opening your MOX’ enclosure on the site where the USB3-port is located.
I’d try to reinstall via flashing new image directly to the microSD-card - procedure is explained in detail here: Preparation of microSD card for Turris MOX [Turris wiki]