Thank you very much. That was the solution for my problem.
On my Ubuntu I solved it as follows:
vi /etc/netplan/00-installer-config.yaml
network:
ethernets:
enp3s0:
dhcp4: true
routes:
- to: 192.168.2.0/24
via: 192.168.4.1
version: 2
after saving
sudo netplan apply
works fine 🙂