I was having problems as well as soon as I did the OTA update this morning. I've been connecting to a Bose Soundlink Mini for months without any issues before the 4.4.3 update. After the update, sound would stutter every 15 seconds or so, and sometimes stop playing entirely. Switching to 2.4 ghz seems to have fixed the problem. I have the Netgear R7000 router, so it's unlikely it's due to both our routers.
When I was connected to 5ghz, the problem was much worse when I opened a Wifi Analyzer app or browsed the internet. Thanks for the switching to 2.4ghz tip, you saved me a few frustrating hours. Already contacted Google and told them the issues, but it was before I tried connecting to 2.4ghz