My morning commute involves 2-3 minutes before my train enters a tunnel for 5-10 minutes. I'd like to check my morning emails in that time, but I never manage to get my laptop to connect to the Amtrak WiFi by then. I had always blamed Amtrak for the problem, until I brought my work Thinkpad one day and it connected immediately.

I'm beginning to suspect the DNS redirection used for the Amtrak WiFi splash page confuses discoveryd.

I've been super disappointed with Yosemite's networking. It takes forever to connect to an access point, and Instant Hotspot works maybe 30% of the time between my rMBP and iPhone 6+.