If it's easy to trigger maybe you could try to downgrade to https://bugs.launchpad.net/ubuntu/+source/wpa/2.4-0ubuntu6.3 to confirm the problem is resolved with that version (so we are sure it's an issue with the wpa update)
If it's easy to trigger maybe you could try to downgrade to https:/ /bugs.launchpad .net/ubuntu/ +source/ wpa/2.4- 0ubuntu6. 3 to confirm the problem is resolved with that version (so we are sure it's an issue with the wpa update)