wlan0 down/up repeatedly

[mdlowry]

I keep having wlan0 dropping and reconnecting due to loss of IPv6 address.

Jul 21 22:23:51 Lenovo avahi-daemon[849]: Withdrawing address record for fe80::120b:a9ff:fec7:2a7c on wlan0.
Jul 21 22:23:51 Lenovo dhclient[7463]: Internet Systems Consortium DHCP Client 4.2.4
Jul 21 22:23:51 Lenovo dhclient[7463]: Copyright 2004-2012 Internet Systems Consortium.
Jul 21 22:23:51 Lenovo dhclient[7463]: All rights reserved.
Jul 21 22:23:51 Lenovo dhclient[7463]: For info, please visit https://www.isc.org/software/dhcp/
Jul 21 22:23:51 Lenovo dhclient[7463]: 
Jul 21 22:23:51 Lenovo dhclient[7463]: Listening on LPF/wlan0/10:0b:a9:c7:2a:7c
Jul 21 22:23:51 Lenovo dhclient[7463]: Sending on   LPF/wlan0/10:0b:a9:c7:2a:7c
Jul 21 22:23:51 Lenovo dhclient[7463]: Sending on   Socket/fallback
Jul 21 22:23:51 Lenovo dhclient[7463]: DHCPREQUEST on wlan0 to 255.255.255.255 port 67 (xid=0x34eaef35)
Jul 21 22:23:51 Lenovo dhclient[7463]: DHCPACK from 10.27.162.65 (xid=0x34eaef35)
Jul 21 22:23:51 Lenovo dhclient[7463]: bound to 10.27.162.71 -- renewal in 4004 seconds.
Jul 21 22:23:51 Lenovo avahi-daemon[849]: Joining mDNS multicast group on interface wlan0.IPv4 with address 10.27.162.71.
Jul 21 22:23:51 Lenovo avahi-daemon[849]: New relevant interface wlan0.IPv4 for mDNS.
Jul 21 22:23:51 Lenovo avahi-daemon[849]: Registering new address record for 10.27.162.71 on wlan0.IPv4.
Jul 21 22:23:52 Lenovo systemd[1]: PID file /run/sendmail.pid not readable (yet?) after start.
Jul 21 22:23:53 Lenovo avahi-daemon[849]: Registering new address record for fe80::120b:a9ff:fec7:2a7c on wlan0.*.

I have no problem with IPv6 on the wired connection, it's just the wireless connection that drops.