Sms and email issues after upgrade to Marshmallow

I am having two presumably related problems since installing Marshmallow on my Nexus5.

Email is downloading only intermittently to my device. Sent messages are sitting queued perpetually. (Gmail app)
SMS take forever to send, sometimes timing-out and I get an alert that it has not sent. Although I seem to receive ok. MMS messages don't send or receive, they just hangup the app which can no longer send or receive anything. (the new Android-Messenger app) Note: I switched from HangOuts because it was not sending at all.

I have scrubbed the caches. I have factory "reset" the device and reinstalled all my apps, connections and settings. I have only a few apps and they are all widely used apps from the GooglePlay store.

There are other reports of similar 'connection' problems on the web, but no seemingly universal solution. Anyone know of anything I've missed?

Thanks.