The Network.Shill.WiFi.ExpiredLeaseLengthSeconds metric in UMA
has a CDF of >50% at 10 seconds. 
The metric logs the # of seconds the DHCP lease was active, before it expired without the client being able to renew it. 
Based on informal chats (needs to be verified)- for an aggressive router, we expect this to be 10-15 minutes, for normal cases, it should be 30 mins to a day.
Instead UMA data shows >50% in under 10 seconds, and two small spikes are 5 minutes and 10 minutes, but none at 30 minutes or higher than that. 

Sameer had reported concerns about DHCP lease renewal upon resume from suspend. This could be related.