Bug#917128: udev 240 breaks network interface naming

[Dragan Tubic]

I have the same problem

 Failed to rename network interface 2 from 'enxXXXXXXXXXXX to 'wan':
Device or resource busy

I noticed the following line in the journal that before udevd fails,

 systemd-networkd[293]: enxXXXXXXXXXXX : IPv6 successfully enabled

so I tried to disable ipv6 in
 /etc/sysctl.conf
by setting

net.ipv6.conf.all.disable_ipv6 = 1

net.ipv6.conf.default.disable_ipv6 = 1

net.ipv6.conf.lo.disable_ipv6 = 1

which after rebooting solved the problem. Not sure if I stumbled upon
the right solution but I hope it helps.