can't access server even from internel console

Welcome to the netcup forums for customers from customers.
First of all you should provide the details of your netcup product - so what server are we talking about. Please also provide what did you change or modify after the default configuration of the server which might have been a Debian 13 trixie installation if it was recently setup. If this problem did already exist after provisioning the easiest way would have been to directly open a support ticket here netcup Support: Contact, Tickets & Phone Help. (but be aware that currently tickets take a long time to resolve and you might have to wait several days in the worst case - so maybe try and resolve this here with the help of other netcup customers which might be able to help out - also feel free to ask your artificial intelligence provider of choice for basic problems)

The screenshot shows the UEFI Interactive Shell v2.2 is a lightweight command-line interface environment built into virtual machines. It appears when your computer or virtual machine cannot find a valid operating system bootloader, meaning no bootable device or valid OS installation was detected. So no Ubuntu latest LTS installation was found and booted and therefore you also do not have SSH access to the machine. It is basically stuck at before booting the operating system.

Instructions on how to use this SCP "stuff" in English to setup your server are here: netcup documentation - servers
Depending on your level of knowledge and server management it might be better to open a ticket to get the issue resolved.

The shell lists block devices, but no partitions.
Partitions/file systems would appear as "FS0", "FS1" etc.
You then could do something like:

fs0:
cd EFI
cd BOOT
bootx64.efi

Perhaps change the type of disk emulation and try again installing. VIRTIO should be ok.