I tried putting Ubuntu in suspend mode and wake it up again after reading https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1939638/comments/11.
This seams to make the situation work again. After bringing the network interface up again and requesting a fresh IP from the DHCP server I'm able to use the USB network adapter again.
I tried putting Ubuntu in suspend mode and wake it up again after reading https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/1939638/ comments/ 11.
This seams to make the situation work again. After bringing the network interface up again and requesting a fresh IP from the DHCP server I'm able to use the USB network adapter again.