virsh net-destroy default <===> The proper way fo changing address is using virsh. You can stop network (e.g. ifdown)
virsh net-start default <===> And you can start it with
virsh net-edit default <===> As you edited default.xml file this should be enough. But for editing you can use
pokud nejde sit zkusit toto FUNGUJE!sudo virsh net-list --allsudo virsh net-start default
