There are broken devices in the wild that handle duplicate IP address
detection by sending out ARP requests for the IP that they received from a
DHCP server and refuse the address if they get a reply.
When proxyarp is enabled, they would go into a loop of requesting an address
and then NAKing it again.
Fixes: https://github.com/openwrt/openwrt/issues/14309
Signed-off-by: Felix Fietkau <nbd@nbd.name>
