Q: MBP Wireless Dropping Out Since Yosemite Upgrade

Since I updated to Yosemite a few months ago on my mid-2009 MBP, my home wireless connection has frequently dropped out and often slowed significantly.  Occasionally it works fine for hours at a time.

Before the Yosemite update, I had had virtually no wireless connection problems (5+ years).

All other wireless devices in the household stay connected fine.

What troubleshooting can I do on the MBP?

(using Time Capsule as router)

Thanks.