Thanks! Your example is much harder to dismiss as a 3rd party problem.
Please write to Apple support:
https://www.apple.com/feedback/
I left them a report for 10.10.2, 10.10.3 and 10.10.3 with the new router. I'm not happy about writing naggy feedback, I don't like to receive those myself, but what else can I do? I'm desperate.
This is an example of what I've sent them:
Every 15 minutes pings timeout to remote addresses for about a minute.
Pings to the router are fine.
All other devices on the router are fine (Windows, Andorid, iPhone, old iPad, Mavericks MBA).
Router is Cisco EPC3925.
I've already sent a similar report for 10.10.2.
Multiple users report the same, with different Macs and router vendors. All Yosemite.
Diagram of the pings: [link]
No particular console log activity.
MacBook works fine on my work Wi-Fi.