I am having a similar problem after upgrading my gateway to 8-419.
The gateway now will not connect reliably on WiFi. It connects just fine on ethernet, but WFi only connects one out of 10-20 (or more) resets.
Application processor is 6-363 (unchanged since November), OTA update (with new OTA updater) goes fine, but no WiFi connection. I have updated via OTA several times with no change.
WiFi config is OK (checked when connected to ethernet), and it does connect to WiFi once every x resets - so the config is fine.
I have it connected right now (but in the wrong location). If I move it to my "optimal" location, I will loose WiFi again, and it took me 10 minutes of continual resets to get WiFi on again.
Any Ideas?