People may find this workaround useful, all I can say is it has worked for me to resolve the slow WiFi and related sync issues on my G3 after the Lollipop V 5 update. As folks have mentioned there seems to be a few IPv6 related issues w/ Lollipop. For folks that use Xfinity internet services and their wireless router, it utilizes IPv6. I tried the following:
1. Log into your wireless router
2. Under Connection on left menu, select Local IP Network
3. Under IPv6 section turn Off the "Stateful" checkbox, Save conffg.
4. Under Troubleshooting on left menu, select Reset/Restore, then select Reset.
5. Your router ill restart and about 1-2 min later should b back up.
6. Turn off Wifi on G3 and turn back on.
I haven't found any issues with any of my devices (PC's, iPad, android) with this setting off. I believe stateless is the usual DHCP standard, and should work well for most devices,if you need static IP's for servers or oter apps this may not be a desirable setting, but again it seems to be working well for my environment.