gateway4 has been deprecated, use default routes instead

The message “gateway4 ist veraltet, verwenden Sie stattdessen Standardrouten” or “gateway6 ist veraltet, verwenden Sie stattdessen Standardrouten” comes from netplan and means the syntax has changed.

In the future, “routes:” should be used for setting the default gateway.

Before:

gateway4: 10.225.192.1
gateway6: fe80::1

After:

routes:
    - to: default
      via: 10.225.192.1
    - to: default
      via: fd00::1

Afterwards, do not forget sudo netplan try or – apply. That’s it.