Electric stove - cooking zones work, oven does not - fuse?

Hello everyone,

we have an old electric stove where the cooktops work, but the oven does not. Since we just took it over, unfortunately, I do not know the history.
Does anyone here know about this?
Are there separate internal fuses for the oven and the cooktops, and could that be the cause?
Or is it more likely to be the heating element or something similar?

Attached is a photo of the back.
Thanks a thousand times in advance and best regards!

Please be so kind and do yourself and us a favor and hire an electrician. Maybe you know someone privately who can take a look at it. Even the supply cable looks like 0.75mm². Maybe it’s also 1.5mm². The regulation requires a minimum of 2.5mm². There are also different connection options as you can see on the sticker. And none of us have a crystal ball to see what it looks like inside your connection box... Remember, electricity makes you small, ugly, and black...

If a timer is present on the electric stove, it may possibly not be set to manual operation. That could be one of the causes.